What follows is the second part of our extensive 50-state of cases precluding plaintiffs from proceeding with claims in the absence of admissible expert support.  Part One was last week.  In most states such rulings originated in medical malpractice and workers’ compensation actions, with the relevant principles broadening to encompass product liability and toxic torts.  We were also pleasantly surprised to see how many of the early decisions establishing the expert support requirement for prescription medical product cases arose from the Bone Screw litigation.  That’s one more gift we left for plaintiffs.  Anyway, here is Part Two, covering from Maryland through Rhode Island.

Maryland

The Maryland Court of Appeals has held that, “lay jurors would not be permitted to draw an inference of negligence without the aid of expert testimony” where a case presents an “issue” of a “complex and technical nature.”  Holzhauer v. Saks & Co., 697 A.2d 89, 96 (Md. 1997).

This is not an “obvious injury” case.  Resolution of the issues of negligence and causation involved in a case of this kind necessarily requires knowledge of complicated matters, including human anatomy, medical science, operative procedures, areas of patient responsibility, and standards of care.  Complex issues of the type generated by a case of this kind should not be resolved by laymen without expert assistance.

Orkin v. Holy Cross Hospital, Inc., 569 A.2d 207, 209 (1990).  “[W]here the cause of an [injury] claimed to have resulted from a negligent act is a complicated medical question involving fact finding which properly falls within the province of medical experts. . ., proof of the cause must be made by such witnesses.”  Wilhelm v. State Traffic Safety Commission, 185 A.2d 715, 719 (Md. 1962) (citations omitted).  See Levitas v. Christian, 164 A.3d 228, 230 (Md. 2017) (“the complex issues of causation in lead paint cases generally require expert testimony”); Aventis Pasteur, Inc. v. Skevofilax, 914 A.2d 113, 135 (Md. 2007) (“a medical expert on specific causation was necessary” because whether vaccines cause autism is “a complex medical question”); Miller v. Mandrin Homes, Ltd., 305 F. Appx. 976, 980 (4th Cir. 2009) (plaintiffs “produced no evidence of medical causation. . . .  The district court properly granted summary judgment.”) (applying Maryland law).

In product liability cases, it is also “well settled that expert testimony is required when the subject of the inference is so particularly related to some science or profession that it is beyond the ken of the average layman.”  Wood v. Toyota Motor Corp., 760 A.2d 315, 319 (Md. Spec. App. 2000) (citations and quotation marks omitted).  “Maryland courts have adopted the general rule that expert testimony is required when the subject of the inference that a product is defective is particularly related to some science or profession that it is beyond the ken of the average layman.”  Jones v. Reichert Jung, Inc., 211 F. Supp.2d 661, 667 (D. Md. 2002) (citing Wood).

[E]xpert testimony is usually necessary since the evidence relating to causation involves technical medical questions beyond the common knowledge of laypersons, and the interaction of a [medical device] with the human body raises technical questions requiring expert testimony.  Thus, if the plaintiff has failed to identify admissible evidence with respect to establishing that the [devices] were defective, and that such defect caused her injuries, then [defendant] is entitled to summary judgment, because each of the tort claims . . . depends upon plaintiff proving both defect, and causation.

Miskin v. Baxter Healthcare Corp., 107 F. Supp.2d 669, 672 (D. Md. 1999) (citations omitted), aff’d, 213 F.3d 632 (4th Cir. 2000) (affirmed “on the reasoning” of the court below).  See John Crane, Inc. v. Linkus, 988 A.2d 511, 522 (Md. App. 2010) (following Wood on causation); American Strategic Insurance Corp. v. Scope Services, Inc., 2017 WL 4098722, at *2 (D. Md. Sept. 15, 2017) (“It is well established under Maryland law that expert testimony is required when the subject of the inference is so particularly related to some science or profession that it is beyond the ken of the average laymen.”) (citation and quotation marks omitted); Osunde v. Lewis, 281 F.R.D. 250, 261 (D. Md. 2012) (“the notion that complicated issues of medical causation require expert testimony is well established in Maryland law”); Selective Insurance Co. v. Empire Comfort Systems, 2007 WL 7681251, at *4 (D. Md. March 21, 2007) (in claims “alleg[ing] the malfunction of complex machinery, expert testimony is required to establish negligence and causation”); Giddings v. Bristol-Myers Squibb Co., 192 F. Supp.2d 421, 423 (D. Md. 2002) (following Miskin); Markey v. Centocor, Inc., 2008 WL 6087370, at *8 (Md. Cir. April 29, 2008) (“Because this case involves numerous drug companies and a drug study . . ., whatever Plaintiffs theory of liability, it necessarily involves a complicated medical question. . . .  Without expert testimony, Plaintiff cannot proceed with her case and the entry of summary judgment in favor of [defendant] would be appropriate.”).

Massachusetts

Massachusetts recognizes that “[m]edical causation has two components, both of which require expert opinion evidence . . . general causation, i.e., that the drug can cause the injury, and specific causation, i.e., that the drug did cause the injury in this case.”  Reckis v. Johnson & Johnson, 28 N.E.3d 445, 461 n.33 (Mass. 2015).  Recognition that medical causation is “a matter beyond the common knowledge of the ordinary layman and proof of it must rest upon expert medical testimony” goes back decades.  Hachadourian’s Case, 162 N.E.2d 663, 666 (Mass. 1959).

The presence of such a defect cannot be inferred in the absence of expert testimony.  The opinion of the nonexperts who testified at trial cannot substitute for this absence of expert testimony.  Lacking expert testimony, other possible causes of the [accident] were not sufficiently eliminated.

Enrich v. Windmere Corp., 616 N.E.2d 1081, 1084 (Mass. 1993) (citations omitted).  “Because understanding medical causation is beyond the . . . knowledge of the ordinary layman . . . proof of it must rest upon expert medical testimony.”  Case of Canavan, 733 N.E.2d 1042, 1051 (Mass. 2000).  Summary judgment is “appropriate” where “[w]ithout the aid of an expert in the field, jurors would also be left to speculate about whether alternatively engineered designs might have prevented the accident.”  Esturban v. Massachusetts Bay Transportation Authority, 865 N.E.2d 834, 836 (Mass. App. 2007).  “[I]f the causation question involves questions of medical science or technology, the jury requires the assistance of expert testimony.”  Held v. Bail, 547 N.E.2d 336, 338 (Mass. App. 1989) (citations omitted).

In product liability cases:

It is also well-settled under Massachusetts law that understanding medical causation is a matter beyond the common knowledge of the ordinary layman and proof of it must rest upon expert medical testimony.  This applies to the requisite showings for both general and specific causation.  Without such expert testimony, a fact finder would have no basis other than conjecture, surmise, or speculation upon which to conclude that the injuries of which a plaintiff complains were caused by the impact of the Defendants’ product.

Jackson v. Johnson & Johnson, 330 F. Supp.3d 616, 625 (D. Mass. 2018) (citations and quotation marks omitted).  See Goffredo v. Mercedes-Benz Truck Co., 520 N.E.2d 1315, 1319 (Mass. 1988) (“[w]ithout the testimony of an expert . . ., the evidence was insufficient to establish that the design of the [product] was defective and that the defect caused” plaintiff’s injuries); Milward v. Rust-Oleum Corp., 820 F.3d 469, 476 (1st Cir. 2016) (“expert testimony is required to establish medical causation”; “This applies to both general and specific causation.”) (applying Massachusetts law); Hochen v. Bobst Group, Inc., 290 F.3d 446, 451 (1st Cir. 2002) (“here the nature of the defect or breach of warranty and its causal relation to the accident were complex and thus appropriately the subject of expert testimony”) (applying Massachusetts law); Carrozza v. CVS Pharmacy, Inc., ___ F. Supp.3d ___, 2019 WL 2913987, at *6 (D. Mass. July 8, 2019) (“in Massachusetts expert testimony is required on highly technical medical issues, including injury causation”) (citation and quotation marks omitted); Williams v. Techtronic Industries North America, Inc., 2014 WL 2865874, at *5 (D. Mass. June 23, 2014), (“In products liability cases, where the causal link between the alleged defect and the accident are beyond the ken of the jury, expert testimony is necessary to defeat summary judgment.”), aff’d, 600 F. Appx. 1 (1st Cir. 2015); Calisi v. Abbott Laboratories, 2013 WL 5441355, at *15 (D. Mass. Sept. 27, 2013) (“Under Massachusetts law, when the nature of the defect or breach of warranty and its causal relation to the [injury is] complex, a plaintiff must introduce expert testimony.”) (citations and quotation marks omitted); Carlucci v. CNH America LLC, 2012 WL 4094347, at *10 (D. Mass. Sept. 14, 2012) (“a plaintiff generally must provide expert testimony when the product is complex or technical such that it is beyond the common knowledge of the jury”); Kerlinsky v. Sandoz Inc., 783 F. Supp.2d 236, 242 (D. Mass. 2011) (“the issue of medical causation requires expert analysis”); Langadinos v. Hosokawa Micron International, Inc., 2011 WL 1213079, at *1 (D. Mass. March 31, 2011) (“given the nature of the injury and complexity of the relevant machinery, expert testimony is necessary to support plaintiff’s claims”); Pritchard v. Stanley Access Technologies, LLC, 2011 WL 309662, at *5 (D. Mass. Jan. 27, 2011) (“a jury could not reasonably conclude, on the basis of the evidence of record and in the absence of expert testimony, that Defendants’ negligence was more likely than not the cause of [plaintiff’s] alleged injuries”) (emphasis original); In re Neurontin Marketing & Sales Practices & Products Litigation, 2010 WL 3169485, at *2 (D. Mass. Aug. 10, 2010) (summary judgment granted where “plaintiff does not have an expert who will testify that [the drug] specifically caused her symptoms”); Morse v. Ford Motor Co., 2010 WL 2773527, at *1 (D. Mass. July 13, 2010) (“In cases involving claims of product defect (such as this case), expert testimony is required because the answers to the highly technical and specialized questions raised by such claims lie outside the knowledge of most lay jurors.”); Alves v. Mazda Motor of America, Inc., 448 F. Supp.2d 285, 301 (D. Mass. 2006) (“As expert evidence is essential to [plaintiff’s] case, the defendants are clearly entitled to prevail now that their evidence is being excluded.”); Polaino v. Bayer Corp., 122 F. Supp.2d 63, 71 (D. Mass. 2000) (“without such [expert] testimony, plaintiff can prove neither a design defect nor causation”).

Michigan

Michigan law has “long recognized the importance of expert testimony . . . to educate the jury and the court regarding matters not within their common purview.”  Locke v. Pachtman, 521 N.W.2d 786, 790 (Mich. 1994).  See Woodard v. Custer, 702 N.W.2d 522, 525 (Mich. 2005) (quoting and following Locke).  Likewise, determining causation in toxic tort cases is “scientific in nature . . . [so] it is to the scientific community that the law must look for the answer.  For this reason, expert witnesses are indispensable.”  Nelson v American Sterilizer Co., 566 N.W.2d 671 (Mich. App. 1996).  “[I]n toxic tort cases involving complex chemicals and their effects on human health, expert testimony is often required because the alleged injuries are not immediately obvious and the connection between exposure and injury is not a matter of common sense or everyday experience.”  Hendrian v. Safety-Kleen Systems, Inc., 2015 WL 4770966, at *4 (E.D. Mich. Aug. 13, 2015) (citation and quotation marks omitted).  See also Lowery v. Enbridge Energy Ltd. Partnership, 898 N.W.2d 906, 917-18 (Mich. 2017) (“expert testimony on causation is necessary in a toxic tort case when the legal proposition is beyond the common knowledge of an ordinary juror”) (Markman, C.J., concurring).

The same is true in product liability.

Plaintiffs have failed to proffer expert evidence . . . to support their contention that [the medical device] . . . caused [the] injuries in this case.  This requires the Court to grant Defendant’s motion for summary judgment. . . .  [E]xpert testimony is indispensable to prove causation where it is to the scientific community that the law must look for the answer.”

Avendt v. Covidien, Inc., 262 F. Supp.3d 493, 532 (E.D. Mich. 2017) (citations and quotation marks omitted).  See Swartz v. Procter & Gamble Manufacturing Co., 2018 WL 2239558, at *5 (E.D. Mich. May 16, 2018) (“expert testimony is required to demonstrate the existence of a reasonable alternative design that would satisfy the elements of a plaintiff’s claim”); In re Dow Corning Corp., 541 B.R. 643, 654 (E.D. Mich. 2015) (“Both causation inquiries − general and specific − involve scientific assessments that must be established through the testimony of a medical expert.”), aff’d, 667 F. Appx. 538 (6th Cir. 2016); Eiben v. Gorilla Ladder Co., 2013 WL 1721677, at *16 (E.D. Mich. April 22, 2013 (“Because the expert’s testimony is inadmissible, . . . Plaintiff’s claim of design defect cannot survive summary judgment.”); Dow v. Rheem Manufacturing Co., 2011 WL 4484001, at *22 (E.D. Mich. Sept. 26, 2011) (“expert testimony on causation is necessary, where the claim presents technical issues that are beyond the common experience and understanding of the common juror.”) (citations and quotation marks omitted), aff’d, 527 F. Appx. 434 (6th Cir. 2013); Gillett v. Sofamor, S.N.C., 2001 WL 1135304, at *6 (E.D. Mich. Sept. 13, 2001) (without expert testimony “Plaintiff has not presented sufficient evidence to establish a prima facie case that an alternative design was available”); Berry v. Crown Equipment Corp., 108 F. Supp.2d 743, 756 (E.D. Mich. 2000) (“In the absence of expert testimony concerning reasonableness of the plaintiff’s proposed alternative design, a manufacturer is entitled to entry of judgment as a matter of law.”).

Minnesota

In Minnesota, “[e]xpert opinion is required to prove causation if the issue is outside the realm of common knowledge.”  Walton v. Jones, 286 N.W.2d 710, 715 (Minn. 1979).

It is well-settled law . . . that the need for positive expert testimony to establish a causal connection between the defendant’s negligent act and the plaintiff’s injury or condition depends upon the nature of the question.  Where the question involves obscure and abstruse medical factors such that the ordinary layman cannot reasonably possess well-founded knowledge of the matter and could only indulge in speculation in making a finding, there must be expert testimony, based on an adequate factual foundation, that the thing alleged to have caused the result not only might have done so, but in fact did cause it.

Stahlberg v. Moe, 166 N.W.2d 340, 345 (Minn. 1969) (citations omitted).  “Where a question involves obscure and abstruse medical factors such that the ordinary [lay person] cannot reasonably possess well-founded knowledge in the matter and could only indulge in speculation . . . there must be expert testimony.”  Gross v. Victoria Station Farms, Inc., 578 N.W.2d 757, 762 (Minn. 1998) (citation and quotation marks omitted).  Thus, “[e]xpert testimony is generally required” in cases that “involve complex scientific or technological issues.”  Mercer v. Andersen, 715 N.W.2d 114, 122 (Minn. App. 2006).

The rule in product liability is the same.  “[P]ersonal injury cases involving pharmaceuticals, toxins or medical devices involve complex questions of medical causation beyond the understanding of a lay person.”  In re Baycol Products Litigation, 321 F. Supp.2d 1118, 1126 (D. Minn. 2004).  “Under Minnesota law, expert testimony is required to prove causation in cases involving complex medical issues with which a jury is unlikely to have experience.”  In re Viagra Products Liability Litigation, 658 F. Supp.2d 950, 968 (D. Minn. 2009) (quoting Johnson v. Zimmer, Inc., 2004 WL 742038, at *6 (D. Minn. March 31, 2004)).  See Fireman’s Fund Insurance Co. v. Canon U.S.A., Inc., 394 F.3d 1054, 1060-61 (8th Cir. 2005) (“Absent the excluded opinions of the . . . experts, [plaintiff] presented no evidence of any defect in the [product].”) (applying Minnesota law); Polski v. Quigley Corp., 2007 WL 2580550, at *11 (D. Minn. Sept. 5, 2007) (“Because the Court will not permit [plaintiffs’ expert] to testify that [the product] caused [their] injuries, [plaintiffs] will not be able to establish causation at trial.”), aff’d, 538 F.3d 836 (8th Cir. 2008); Rye v. Matrixx Initiatives, Inc., 2007 WL 2475960, at *4 (D. Minn. Aug. 24, 2007) (also quoting Johnson); Willert v. Ortho Pharmaceutical Corp., 995 F. Supp. 979, 983 (D. Minn. 1998) (“the present case involves such obscure and abstruse medical questions requiring competent expert testimony”).

Mississippi

In Mississippi litigation, “[e]xpert testimony is required unless the matter in issue is within the common knowledge of laymen.”  Denham v. Holmes, 60 So.3d 773, 789 (Miss. 2011) (quoting Palmer v. Biloxi Regional Medical Center, Inc., 564 So.2d 1346, 1355 (Miss. 1990)). “ In all but the simple and routine cases, it is necessary to establish medical causation by expert testimony.”  Short v. Wilson Meat House, LLC, 36 So.3d 1247, 1253 (Miss. 2010) (citation and quotation marks omitted).  Thus, “Mississippi law requires expert medical testimony where causation is an issue in a complicated case because such determinations are generally outside the scope of the average experiences and qualifications of most lay jurors.”  Brown v. Eli Lilly & Co., 654 F.3d 347, 358 (2d Cir. 2011) (applying Mississippi law).

Similar holdings under Mississippi law have occurred in product liability and toxic tort cases.  See Savage v. Pilot Travel Centers, L.L.C., 464 F. Appx. 288, 290 (5th Cir. 2012) (“Under Mississippi law, actions involving ‘medically complicated’ injuries require expert testimony on causation.”) (applying Mississippi law); Hill v. Koppers, Inc., 2009 WL 4908836, at *7-8 (N.D. Miss. Dec. 11, 2009 (Daubert exclusion of plaintiff’s experts created a “complete failure of proof . . . on general and specific causation”); Berry v. Southwest Airlines Co., 2008 WL 3874368, at *3 (S.D. Miss. Aug. 15, 2008) (“with injuries that are medically complicated, as is the case here, expert testimony is required to prove causation”); Jackson v. Bayer Corp., 2007 WL 2580379, at *4 (S.D. Miss. Sept. 4, 2007) (applying Mississippi law) (plaintiffs “have not offered any expert proof at all . . . that [the drug] caused or contributed to the plaintiffs’ alleged injuries and damages.  Failure to offer evidence on a critical matter upon which they bear the burden is fatal to their case”).

Missouri

Under the law of Missouri, “[m]edical causation, which is not within common knowledge or experience, must be established by scientific or medical evidence showing the relationship between the complained of condition and the asserted cause.”  Malam v. State, Dept. of Corrections, 492 S.W.3d 926, 929 (Mo. 2016) (quoting Gordon v. City of Ellisville, 268 S.W.3d 454, 461 (Mo. App. 2008)).

When a fact at issue is so technical or complex that no fact finder could resolve the issue without expert testimony, expert testimony is necessary and, therefore, required.  For example, expert testimony has been required to explain the results of medical tests and blood work . . . or to establish causation when there is a sophisticated injury that involves a highly scientific technique for diagnosis.

Stone v. Missouri Dept. of Health & Senior Services, 350 S.W.3d 14, 21 (Mo. 2011) (citations and quotation marks omitted).  “Proof of causation generally requires expert testimony to establish the causal connection between the accident and the injury.”  Host v. BNSF Railway Co., 460 S.W.3d 87, 104 (Mo. App. 2015).

This rule is applied in toxic tort and product liability litigation.  “[C]ausation in cases involving exposure to a toxic substance typically requires a certain degree of scientific expertise.”  Brown v. Seven Trails Investors, LLC, 456 S.W.3d 864, 869 (Mo. App. 2014).  “The nature of [a] medication’s side effects, the doses necessary to manifest those effects, and the biomedical interaction of [different] medications are all matters beyond that of a layperson’s common knowledge and experience.”  Love v. Waring, 560 S.W.3d 614, 620 (Mo. App. 2018).  “[E]xpert testimony is necessary” in product liability cases where “the lay jury [does] not possess the experience or knowledge of the subject matter sufficient to enable them to reach an intelligent opinion without help.”  Pro Service Automotive, L.L.C. v. Lenan Corp., 469 F.3d 1210, 1214 (8th Cir. 2006) (applying Missouri law) (quoting Wright v. Barr, 62 S.W.3d 509, 524 (Mo. App. 2001)).  See Redd v. DePuy Orthopaedics, Inc., 700 F. Appx. 551, 555 (8th Cir. 2017) (summary judgment affirmed because “the fracture of [plaintiff’s] . . . implant was a sophisticated injury, and [plaintiff] lacked any admissible expert testimony on the cause of that fracture”) (applying Missouri law); Menz v. New Holland North America, Inc., 507 F.3d 1107, 1112 (8th Cir. 2007) (“The district court did not abuse its discretion in concluding a lay jury would lack the experience and knowledge necessary to determine causation on [plaintiff’s] warnings claim without the aid of expert testimony.”) (applying Missouri law); Turner v. Iowa Fire Equipment Co., 229 F.3d 1202, 1210 (8th Cir. 2000) (“Without [an expert] opinion that the [product] exposure caused the . . . injuries, [plaintiffs] cannot prove causation.”) (applying Missouri law); Howard v. Bosch Thermotechnology Corp., 2018 WL 2087259, at *3 (E.D. Mo. May 4, 2018) (expert testimony “is necessary if determining a relevant factual issue involves information that is so complex or technical that no fact finder could resolve the issue without help”); Hoover v. Bayer Healthcare Pharmaceuticals, Inc., 2017 WL 2313177, at *4 (W.D. Mo. Jan. 11, 2017) (“Without reliable expert testimony concerning specific causation . . ., the Court concludes Plaintiff is unable to establish the necessary element of causation.”); Martin v. Crown Equipment Corp., 2008 WL 11337826, at *3 (W.D. Mo. Jan. 16, 2008) (“[w]hen a failure-to-warn claim involves technical and complex machinery not commonly utilized by typical lay jurors, it is appropriate for the Court to require expert testimony”); Hilton v. Ethicon, Inc., 2007 WL 541603, at *3 (W.D. Mo. Feb. 16, 2007) (“Without such expert testimony, Plaintiff cannot establish causation.”); Looney v. Zimmer, Inc., 2004 WL 1918720, at *5 (W.D. Mo. Aug. 19, 2004) (“When an injury is sophisticated, proof of causation generally must be established by expert testimony.”); Shaffer v. Amada America, Inc., 335 F. Supp.2d 992, 998 (E.D. Mo. 2003) (plaintiff “needs competent expert testimony to establish that this [product] is defective and unreasonably dangerous”); Glastetter v. Novartis Pharmaceuticals Corp., 107 F. Supp.2d 1015, 1045 (E.D. Mo. 2000) (Daubert exclusion of plaintiff’s experts created “the absence of any scientifically valid evidence supporting plaintiffs’ theory of causation,” requiring summary judgment), aff’d, 252 F.3d 986 (8th Cir. 2001);  Eppler v. Ciba-Geigy Corp., 860 F. Supp. 1391, 1395 (W.D. Mo. 1994) (in “a product liability action of a highly technical and scientific nature, expert testimony is essential to establish causation”).

Montana

In Montana, matters “not readily apparent to a layman” “obligate[ the plaintiff] to present expert testimony.”  Dubiel v. Montana Dep’t of Transportation, 272 P.3d 66, 70 (Mont. 2012).  “[E]xpert testimony is required when the issue presented is sufficiently beyond the common experience of the trier of fact and the expert testimony will assist the trier of fact in determining the issue or understanding the evidence.”  Hinkle v. Shepherd School Dist. No. 37, 93 P.3d 1239, 1246 (Mont. 2004).  Accord Dayberry v. City of East Helena, 80 P.3d 1218, 1220-21 (Mont. 2003) (same language).

A Plaintiff’s testimony alone is not sufficient “to establish causation of the injury where the nature of the injury is such that laymen can neither plainly see, nor infer from the injury. . . .  Rather, qualified medical testimony from an expert witness is necessary to prove the cause … of such injuries.”

Green v. Montana Dep’t of Public Health & Human Services, 2014 WL 12591834, at *6 (D. Mont. Jan. 3, 2014) (quoting Bleek v. Supervalu, Inc., 95 F. Supp.2d 1118, 1121 (D. Mont. 2000)).  See Horob v. McCone County, 2010 WL 5441961, at *1 (D. Mont. Dec. 28, 2010) (“evidence of causation must be proved with expert medical testimony unless the cause of injury is obvious”), aff’d, 507 F. Appx. 679 (9th Cir. 2013); Wilderness Development, LLC v. Hash, 606 F. Supp.2d 1275, 1281 (D. Mont. 2009) (“the causation issue will require the trier of fact to resolve issues beyond the common experience and knowledge of lay people and, thus, expert testimony will be required”).

The same is true in product liability and toxic tort cases.  In a prescription drug case the Montana Supreme Court held:

There are no Montana cases specifically holding that a plaintiff must produce expert testimony to sustain an action against a drug company for failure to warn adequately of side effects of its products.  There are, however, numerous Montana decisions to the effect that, in a malpractice suit . . . , expert evidence is the only proper guide and without it a plaintiff cannot recover.  We hold that the reasoning of these decisions extends to the situation involved here.  In matters with respect to which a layman can have no knowledge at all, the court and jury must be dependent on expert evidence.  The adequacy of a warning directed to physicians is such a matter.

Hill v. E.R. Squibb & Sons, 592 P.2d 1383, 1388 (Mont. 1979) (citations omitted).  Where a product liability “case involves matters beyond the common experience of a lay juror . . ., summary judgment dismissal is warranted if the plaintiff fails to present expert testimony necessary to prove the elements of his negligence claim.”  Stacy v. BNSF Railway Co., 2015 WL 1433679, at *2 (D. Mont. March 27, 2015).  See Wilhelm v. Pfizer, Inc., 2016 WL 5030359, at *4 (D. Nev. Sept. 19, 2016) “the Court finds that expert testimony is required to establish causation as to all of [plaintiff’s] claims”) (applying Montana law); Brumbaugh v. Sandoz Pharmaceutical Corp., 77 F. Supp.2d 1153, 1157 (D. Mont. 1999) (without expert testimony, “plaintiff is unable to generate a genuine issue of material fact with respect to causation, an essential element of her claim”).

Nebraska

Nebraska courts hold that “[e]xpert testimony is almost always required to prove proximate causation.”  Ewers v. Saunders County, 906 N.W.2d 653, 664 (Neb. 2018) (quoting Thone v. Regional West Medical Center, 745 N.W.2d 898, 908 (Neb. 2008)).  Medically complicated questions requir[e] expert testimony” so that “the cause and extent of [plaintiff’s] injuries must be substantiated by expert testimony.”  Doe v. Zedek, 587 N.W.2d 885, 891-92 (Neb. 1999).  “Unless its nature and effect are plainly apparent, an injury is a subjective condition requiring an expert opinion to establish a causal relationship between the incident and the injury or disability.”  Bernhardt v. County of Scotts Bluff, 482 N.W.2d 262, 263 (Neb. 1992) (syllabus).

[W]here the claimed injuries are of such a character as to require skilled and professional persons to determine the cause and extent thereof, the question is one of science.  Such a question must necessarily be determined from testimony of skilled professional persons and cannot be determined from the testimony of unskilled witnesses having no scientific knowledge of such injuries.

Hohnstein v. W.C. Frank, 468 N.W.2d 597, 602 (Neb. 1991).

In product liability cases, “[e]xpert evidence is required to establish the elements of causation and defect.”  Barrett v. Rhodia, Inc., 606 F.3d 975, 984 (8th Cir. 2010) (applying Nebraska law).  Like other “cases involving complex technical, medical, or scientific issues, causation must be established by expert testimony.”  Vallejo v. Amgen, Inc., 274 F. Supp.3d 922, 925 (D. Neb. 2017), aff’d, 902 F.3d 733 (8th Cir. 2018).

Ordinarily, in medical cases, product defect and medical causation must be established by expert testimony.  Similarly, the lack of expert testimony on the question of causation results in an insufficiency of proof where the issue involves technical, scientific or medical matters which are beyond the common knowledge or experience of jurors and the jury could only speculate as to what inference to draw.  Where the exact nature and probable genesis of a particular type of injury involves complicated medical questions far removed from the ordinary experience and knowledge of laymen, only an expert can give competent opinion evidence as to the cause of the injury.

Uribe v. Sofamor, S.N.C., 1999 WL 1129703, at *7 (D. Neb. Aug. 16, 1999) (citations, quotation marks, and footnote omitted).  See Schafersman v. Agland Coop, 681 N.W.2d 47, 56 (Neb. 2004) (“the court correctly entered summary judgment” in product liability case after excluding plaintiff’s experts); “whether or not a drug causes an individual to [suffer injury] is a complex factual question”; Grant v. Pharmative, LLC, 452 F. Supp.2d 903, 910 (D. Neb. 2006) (“Without evidence to establish both general and specific causation, plaintiffs cannot survive defendants’ motions for summary judgment.”); Nuzum v. Chlorella, 2006 WL 3825111, at *2 (D. Neb. Dec. 27, 2006) (“the plaintiff cannot establish essential elements of his products liability claim without expert testimony”).

Similarly, “expert testimony was necessary to establish the basis for an inference that [plaintiff’s] injuries were caused by the inhalation of fumes.”  McNeel v. Union Pacific Railroad Co., 753 N.W.2d 321, 329 (Neb. 2008).  “In a toxic tort case, the plaintiff’s expert evidence must show that the toxin was the cause of the plaintiff’s injury.”  Barrett, 606 F.3d at 984 (citation and quotation marks omitted).

Nevada

Under Nevada law, “generally, because an injury is a subjective condition, an expert opinion is required to establish a causal connection between the incident or injury and disability.”  Grover C. Dils Medical Center v. Menditto, 112 P.3d 1093, 1100 (Nev. 2005).  “[I]f the plaintiff’s medical expert cannot form an opinion . . ., there is nothing on the record with which a jury can make a decision.”  Morsicato v. Sav-On Drug Stores, Inc., 111 P.3d 1112, 1116 (Nev. 2005) (citation and quotation marks omitted).  “Causation in toxic tort litigation is generally proven by expert testimony.”  Jernee v. Kennametal, Inc., 2015 WL 134767, at *1 (Nev. Jan. 8, 2015) (unpublished).  “When, as here, the cause of injuries is not immediately apparent, the opinion as to the cause should be given by one qualified as a medical expert.”  Lord v. State, 806 P.2d 548, 551 (Nev. 1991).

[Plaintiff] failed to timely disclose any expert witness or treating physician to testify regarding causation. . . .  Since [plaintiff] could not show causation, he failed to establish each element of his negligence claims.  Thus, summary judgment was appropriate.

Elliott v. City Center Veer Towers Development, LLC, 2018 WL 2041490, at *2 (Nev. App. April 20, 2018) (also quoting and following Grover).

Thus, “[u]nder Nevada law, Plaintiffs must produce medical expert testimony to establish causation, particularly where the cause of death is not immediately apparent.”  Neal-Lomax v. Las Vegas Metro. Police Dep’t, 574 F. Supp.2d 1193, 1199 (D. Nev. 2008), aff’d, 371 F. Appx. 752 (9th Cir. 2010).  See Elliott v. Prescott Cos., LLC, 2018 WL 3731087, at *5 (D. Nev. Aug. 6, 2018) (“the causal relationship between [the] chemicals and [plaintiff’s] alleged injuries is not immediately apparent or within the comprehension of the ordinary layperson.  As such, expert testimony is required to prove causation.”); Blackmon v. New Albertson’s Inc., 2012 WL 3613956, at *3 (D. Nev. Aug. 21, 2012) (“Nevada law requires an expert opinion to establish a causal connection between the incident and the injury.”); Thompson v. TRW Automotive, Inc., 2015 WL 5474448, at *5 (D. Nev. Sept. 17, 2015) (“expert testimony . . . is necessary because the issues are complicated and often far beyond an ordinary juror’s understanding”) (citation and quotation marks omitted), aff’d, 694 F. Appx. 566 (9th Cir. 2017); Blackmon v. New Albertson’s, Inc., 2011 WL 4958631, at *2 (D. Nev. Oct. 17, 2011) (“It is well-settled law that in a personal injury action causation must be proven within a reasonable medical probability based upon competent medical testimony.”) (citation and quotation marks omitted); Duenas v. United States, 2006 WL 8441980, at *5 (D. Nev. Feb. 15, 2006) (“On the basis that Plaintiff has failed to put forth reliable medical expert testimony or treatises as to injuries, we will grant Defendant’s motion for summary judgment”); Layton v. Yankee Caithness Joint Venture, L.P., 774 F. Supp. 576, 580 (D. Nev. 1991) (“[W]here a question of fact is beyond the comprehension of the ordinary lay person, expert testimony is required to prove that fact.”).

New Hampshire

New Hampshire law holds that “[e]xpert testimony is required where the subject presented is so distinctly related to some science, profession or occupation as to be beyond the ken of the average layperson.”  Estate of Sicotte v. Lubin & Meyer, P.C., 959 A.2d 236, 239 (N.H. 2008).  “The medical causation of [an . . .] injury of this nature is a matter properly within the province of medical experts.”  Appeal of Briggs, 645 A.2d 655, 659 (N.H. 1994).

To determine whether expert testimony is required, we must determine whether this issue . . . is within the realm of common knowledge and everyday experience of the average layman, or whether an expert opinion is needed to preclude the jury from engaging in idle speculation. . . .  Expert testimony is required if any inference of the requisite causal link must depend on observation and analysis outside the common experience of jurors.

Stachulski v. Apple New England, LLC, 191 A.3d 1231, 1241 (N.H. 2018) (citations and quotation marks omitted).  See Smith v. HCA Health Services, Inc., 977 A.2d 534, 539 (N.H. 2009) (“The plaintiffs’ claims are actions for medical injury that require expert testimony”); Carbone v. Tierney, 864 A.2d 308, 315 (N.H. 2004) (“The facts of this case are thus sufficiently complicated to require expert testimony with respect to causation.”); Sawyer v. Purdue Pharmaceutical Corp., 2013 WL 6840145, at *7 (M.D. Pa. Dec. 27, 2013) (“[o]nly a qualified expert could provide the jury an informed basis upon which to conclude that [defendant] did not exercise reasonable care in the manufacture and design of [its drug]”; “the jury could reasonably conclude that [defendant] provided inadequate warnings only with the help of expert opinion”) (applying New Hampshire law); Grimes v. Hoffmann-LaRoche, Inc., 907 F. Supp. 33, 38-39 (D.N.H. 1995) (granting summary judgment in prescription medical product liability action after exclusing plaintiff’s expert).

New Jersey

A plaintiff in New Jersey is “required to produce an expert” when the case involves “a complex process involving assessment of a myriad of factors that is beyond the ken of the average juror.”  Davis v. Brickman Landscaping, Ltd., 98 A.3d 1173, 1180 (N.J. 2014).

[C]ertain claims require expert testimony.  In tort actions, whether expert testimony is needed in respect of breach of duty depends on whether the matter to be dealt with is so esoteric that jurors of common judgment and experience cannot form a valid judgment about a party’s conduct.  Similarly, cases have found expert testimony to be required in certain types of actions in connection with proof of other tort elements.

Phillips v. Gelpke, 921 A.2d 1067, 1073 (N.J. 2007) (citations and quotation marks omitted).

Thus, “New Jersey law does require expert testimony, however, in cases where lay jurors confront causation issues that are too complex to be understood without the assistance of specialized expert testimony.”  Tormenia v. First Investorrs Realty Co., 251 F.3d 128, 132 (3d Cir. 2000) (applying New Jersey law) (emphasis original).  Tormenia followed Kelly v. Borwegen,

[W]here a claimed disability is the natural result of the injuries sustained, the jury may, without expert opinion, find that the injuries caused such disability.  However, when an injury is such as to require skilled men to determine its cause and extent, the question is one of science, and must be established by skilled professional persons.

230 A.2d 532, 534 (N.J. Super. App. Div. 1967) (citation and quotation marks omitted).  Similarly, “[w]here the allegedly defective product involves a complex instrumentality, a plaintiff is required to provide expert testimony,” since “[e]xpert testimony is necessary to assist the fact finder in understanding ‘the mechanical intricacies of the instrumentality.”  Lauder v. Teaneck Volunteer Ambulance Corps, 845 A.2d 1271, 1277 (N.J. Super. App. Div. 2004).  “A factfinder should not be allowed to speculate without the assistance of expert testimony in an area where the average person could not be expected to have sufficient knowledge or experience.”  State v. Doriguzzi, 760 A.2d 336, 341 (New Jersey Super. App. Div. 2000) (citation omitted).  A more recent decision of the same court agrees:

The topic is plainly outside the common knowledge of the average juror.  Plaintiff needed a medical expert to address these key issues of medical causation, but did not retain one.  This critical shortcoming pertains as to both the wrongful death claim and the survival claim. . . .  [A] lay inference is simply not enough to get the complex issues of medical causation before a jury.

Quail v. Shop-Rite Supermarkets, Inc., 188 A.3d 348, 358 (N.J. Super. App. Div. 2018) (citation omitted).

New Jersey’s expert testimony requirement also applies in product liability and toxic tort cases.  “[W]e hold that in toxic-tort litigation, a scientific theory of causation . . . must be proffered by an expert who is sufficiently qualified.”  Rubanick v. Witco Chemical Corp., 593 A.2d 733, 747-48 (N.J. 1991).  “It is well-settled law that where the allegedly defective product involves a complex instrumentality, a plaintiff is required to provide expert testimony.”  Toms v. J.C. Penney Co., 2007 WL 2893052, at *4 (D.N.J. Sept. 28, 2007), aff’d, 304 F. Appx. 121 (3d Cir. 2008).  “When the proofs involve a defect in a complex instrumentality, an expert is frequently required to assist the jury in understanding the mechanical intricacies and weighing competing theories of causation.”  Ford Motor Credit Co., LLC v. Mendola, 448 A.3d 366, 372 (N.J. Super. App. Div. 2012) (citing Lauder).

Courts generally recognize that plaintiffs in products liability cases must offer admissible expert testimony regarding both general causation and specific causation. . . .  Expert testimony is generally required in product liability cases because it prevents the jury from engaging in speculation in determining the causal link between using or ingesting the product and the injuries complained of following that use.  Determining that causal link typically requires complex medical information beyond the knowledge, understanding, and experience of a lay juror.  Expert testimony typically provides this link.

In re Benicar (Olmesartan) Products Liability Litigation, 2016 WL 6652358, at *2 (D.N.J. Nov. 9, 2016) (citations omitted).  See Ace Pallet Corp. v. Consolidated Rail Corp., 764 F. Appx. 197, 199 (3d Cir. 2019) (affirming summary judgment under Tormenia following exclusion of plaintiff’s experts) (applying New Jersey law); Koplove v. Ford Motor Co., 795 F.2d 15, 18 (3d Cir. 1986) (“a rational jury could not find the defendant liable without some expert analysis of the available information which implicated it”); Huddell v. Levin, 537 F.2d 726, 736 (3d Cir. 1976) (“where the issue concerns a product’s design . . . expert opinion is the only available method to establish defectiveness”) (applying New Jersey law); Hettinger v. Speedline Technology, Inc., 2014 WL 5410620, at *5 (D.N.J. Oct. 22, 2014) (“In the instant matter, an expert opinion is required to prove this vital element of causation for both the design defect and failure to warn claims because the [product] constitutes a ‘complex instrumentality.’”); Sampson v. Glock, Inc., 2014 WL 1225581, at *3 (D.N.J. March 24, 2014) (“given the complex nature of the [product], Plaintiff must rely on the testimony of an expert”); Leese v. Martin, 2013 WL 5476415, at *8 (D.N.J. Sept. 30, 2013) (“As a general proposition, expert testimony is required to demonstrate causation in toxic tort cases.”) (citations omitted); Mays v. General Binding Corp., 2013 WL 1986393, at *6 (D.N.J. May 10, 2013) (quoting Lauder), aff’d, 565 F. Appx. 94 (3d Cir. 2014); Sanders v. Rosenberg, 2008 WL 1732980, at *3 (D.N.J. April 10, 2008) (“in cases concerning toxic torts . . ., testimony of an expert is required, in particular with regard to causation”); Amico v. Duracal Cement, 2006 WL 2319313, at *7 (D.N.J. Aug. 9, 2006) (“Without expert medical testimony there is no evidence of causation to support any of [plaintiff’s] negligence/products liability claims.”); Appleby v. Glaxo Wellcome, Inc., 2005 WL 3440440, at *7 (D.N.J. Dec. 13, 2005) (“Without an expert, it is impossible to evaluate the evidence to ascertain whether the risk of [the drug] sufficiently outweighs its benefit”); Ortiz v. Yale Materials Handling Corp., 2005 WL 2044923, at *2 (D.N.J. Aug. 24, 2005) (“Where the allegedly defective product involves a complex instrumentality, a plaintiff is required to provide expert testimony.”); In re Norplant Contraceptive Products Liability Litigation, 215 F. Supp.2d 795, 830 (E.D. Tex. 2002) (“Evidence of general causation must be provided in the form of expert testimony.”) (citations omitted) (applying New Jersey law); Snodgrass v. Ford Motor Co., 2001 WL 37118915, at *5 (D.N.J. Aug. 31, 2001) (“Where a plaintiff fails to come forward with an expert’s report on a complicated causation issue, summary judgment is appropriate.”); Rutigliano v. Valley Business Forms, 929 F. Supp. 779, 783 (D.N.J. 1996) (“Plaintiff’s case requires expert testimony to satisfy her burden with respect to both general causation and specific causation.”), aff’d, 118 F.3d 1577 (3d Cir. 1997).

New Mexico

Expert testimony in New Mexico “is required to establish an element of a claim or defense [because] it would assist the jury to understand issues in the case that are beyond their knowledge.”  State v. Campbell, 157 P.3d 722, 725 (N.M. 2007).  “To prove a proposition to a reasonable medical probability requires expert medical testimony establishing that the proposition is more likely than not.”  Baca v. Bueno Foods, 766 P.2d 1332, 1334 (N.M. 1988) (citation omitted).  With “issues involv[ing] a complex professional assessment.  It follows that jurors would also require expert testimony.”  Holley v. Evangelical Lutheran Good Samaritan Society, 588 F. Appx. 792, 796 (10th Cir. 2014) (applying New Mexico law).  Where “expert knowledge is essential to the formation of an intelligent opinion, only an expert can competently give opinion evidence as to the cause of death, disease, or a physical condition.”  Woods v. Brumlop, 377 P.2d 520, 522 (N.M. 1962).  See Holley v. Evangelical Lutheran Good Samaritan Society, 588 F. Appx. 792, 796 (10th Cir. 2014) (summary judgment affirmed where issues were “not within the common knowledge ordinarily possessed by an average person,” and plaintiff’s expert excluded) (applying New Mexico law); Montoya v. Ramos, 2017 WL 5654791, at *1 (D.N.M. Sept. 25, 2017) (“diagnoses of complex mental conditions are generally beyond the common experience of lay persons and require special skill or knowledge”); Safford v. Wal-Mart Stores, Inc., 2017 WL 2306410, at *6 (D.N.M. Feb. 16, 2017) (“plaintiffs cannot prevail on the issue of medical causation without expert testimony directly supporting their conclusion”) (citation omitted); American Mechanical Solutions, L.L.C. v. Northland Process Piping, Inc., 184 F. Supp.3d 1030, 1067 (D.N.M. 2016) (“when the issue of causation . . . cannot be determined by resort to common knowledge that an average person ordinarily possesses, New Mexico law requires expert testimony”); Duke v. Garcia, 2014 WL 1333151, at *3 (D.N.M. Feb. 28, 2014) (“the medical situation is complex, and actions involving medically complicated injuries require expert testimony on causation”) (citation and quotation marks omitted).

Similar considerations mandate reliance on expert witnesses in product liability and toxic tort cases in New Mexico.  In “toxic tort cases like the one before us, the determination of the external cause of a patient’s disease is a complex process . . . which requires specialized scientific knowledge regarding the external agents involved.”  Parkhill v. Alderman-Cave Milling & Grain Co., 245 P.3d 585, 590 (N.M. App. 2010).  Thus, in Firstenberg v. Monribot, 350 P.3d 1205 (N.M. App. 2015), another toxic tort case, the court, “[h]aving concluded that [plaintiff’s] arguments regarding . . . expert witness rulings provide no basis for reversal, . . . further conclude[d] that the court properly granted summary judgment in favor of Defendants.”  Id. at 1215.  Likewise, Farris v. Intel Corp., 493 F. Supp.2d 1174 (D.N.M. 2007), held:

General causation and specific causation are essential elements of Plaintiff’s prima facie case for each claim asserted in this litigation.  Expert testimony is necessary to make this showing since this is a toxic tort lawsuit.

Id. at 1186 (citation omitted).  Similarly, in R.R. v. Dandade, 2017 WL 2117386 (N.M. App. April 25, 2017), plaintiff had no expert to establish the relevant injury was drug related.  Thus, “[t]he district court properly granted summary judgment” because “a determination of the external cause of a patient’s condition requires specialized, scientific knowledge regarding those external agents involved.”  Id. at *6 (citation omitted).  See Derrick v. Standard Nutrition Co., 2019 WL 2024960, at *7 (D.N.M. May 8, 2019) (“Such medical knowledge is, as a matter of law, outside the realm of common experience.  Because Plaintiffs have not secured expert testimony on causation, they cannot withstand Defendant’s motion for summary judgment.”).

New York

The New York Court of Appeals was one of the first courts to articulate the modern requirement for expert testimony in tort cases in Meiselman v. Crown Heights Hospital:

[E]xpert medical opinion evidence . . . is required, when the subject-matter to be inquired about is presumed not to be within common knowledge and experience and when legal inference predominates over statement of fact . . .; but where the matters are within the experience and observation of the ordinary jurymen from which they may draw their own conclusions and the facts are of such a nature as to require no special knowledge or skill, the opinion of experts is unnecessary.

34 N.E.2d 367, 370 (N.Y. 1941).  See Fiore v. Galang, 478 N.E.2d 188, 189 (N.Y. 1985)  (error under Meiselman not to grant summary judgment because “expert medical opinion evidence is required to demonstrate merit” ).

Thus, in New York, “to establish causation, [Plaintiffs] must offer admissible expert testimony regarding both general causation . . . and specific causation.”  Amorgianos v. National Railroad Passenger Corp., 303 F.3d 256, 268 (2d Cir. 2002) (applying New York law).  It is a “well-established requirement that an expert opinion on causation set forth a plaintiff’s exposure to a toxin, that the toxin is capable of causing the particular illness (general causation) and that plaintiff was exposed to sufficient levels of the toxin to cause the illness (specific causation).”  In re New York City Asbestos Litigation, 11 N.Y.S.3d 416, 426 (N.Y. Sup. 2015).  See Fitzpatrick v. Currie, 861 N.Y.S.2d 431, 434 (N.Y. App. Div. 2008) (“While the opinion of an expert may not always be necessary in establishing a products liability case, the complex issues involved in the design and operation of [this product] make expert proof imperative.”); Marazzo v. Gilbert, 542 N.Y.S.2d 793, 794 (N.Y. App. Div. 1989) (“It was incumbent upon the plaintiff to elicit expert medical testimony . . . and, in the absence of such testimony on the issue of causation, the claim was properly dismissed”); Glowczenski v. Taser International, Inc., 594 F. Appx. 723, 725 (2d Cir. 2014) (“absent an expert . . . [plaintiffs] cannot prevail on either their products liability or wrongful death claims” because plaintiffs’ “tort claims against [defendant] fail for want of evidence on causation”) (applying New York law); Alaimo v. 3M Co., 306 F. Appx. 704 (2d Cir. 2009) (plaintiffs “were required to prove a causal link between use of the [product] at issue and the injury . . . by use of expert testimony”) (applying New York law); Brooks v. Outboard Marine Corp., 234 F.3d 89, 92 (2d Cir. 2000) (“summary judgment was properly granted” where plaintiff’s expert was excluded; plaintiff “has no evidence in the record to support his [design defect] theory”) (applying New York law); Williams v. Coca Cola Co., 2018 WL 3069208, at *5 (N.D.N.Y. June 21, 2018) (“[g]iven plaintiff’s failure to offer any expert proof on the issue of general and/or specific causation, defendant’s motion for summary judgment is granted”); Young v. Southwest Airlines Co., 2017 WL 1247921, at *3 (E.D.N.Y. Feb. 3, 2017) (“the medical effect on the human system of the infliction of injuries is not generally within the sphere of the common knowledge of the lay person”); Jaquez v. Flores, 2016 WL 1267780, at *4 (S.D.N.Y. March 30, 2016) (“Plaintiffs are thus required to produce admissible expert medical evidence on causation in order to sustain their wrongful death claim. They have chosen not to do so.”); Mallozzi v. EcoSMART Technologies, Inc., 2013 WL 2415677, at *14 (E.D.N.Y. May 31, 2013) (“Without . . . expert testimony, plaintiff cannot establish that the product was the proximate cause of plaintiff’s injuries.”); Kennedy v. New York Presbyterian Hospital, 2011 WL 2847839, at *4 (S.D.N.Y. July 6, 2011) (summary judgment granted; “Plaintiff must − but did not − submit expert medical opinion supporting her theory of causation”).  Also, “Under New York law, a plaintiff seeking to establish a design defect is generally required to provide expert testimony as to the feasibility and efficacy of alternative designs.”  Cuntan v. Hitachi KOKI USA, Ltd., 2009 WL 3334364, at *6 (E.D.N.Y. Oct. 15, 2009) (collecting cases).  See Guarascio v. Drake Associates, Inc., 582 F. Supp.2d 459, 463 (S.D.N.Y. 2008) (same).

In prescription medical product cases, where the plaintiff “suffered a complex injury,” expert testimony was essential.

Implantation of the . . . device involved complicated surgery.  Additionally, the . . . device implanted in [plaintiff] was not one with which an ordinary person would come in contact.  The issue of causation in such a complicated medical case, therefore, was one beyond the sphere of the ordinary juryman and required expert testimony.

Fane v. Zimmer, Inc., 927 F.2d 124, 131 (2d Cir. 1991) (applying New York law).  See Sura v. Zimmer, Inc., 768 F. Appx. 58, 59 (2d Cir. 2019) (in medical device case, “determining the cause of these symptoms is beyond the experience and observation of the ordinary jury, [plaintiff] needed expert testimony”); N.K. v. Abbott Laboratories, 731 F. Appx. 24, 27 (2d Cir. 2018) (“New York law requires expert witnesses to establish specific causation.”) (citing Meiselman); Tomaselli v. New York & Presbyterian Hospital, 728 F. Appx. 41, 43 (2d Cir. 2018) (following Fane in medical device case) (applying New York law); Donovan v. Centerpulse Spine Tech, Inc., 416 F. Appx. 104, 106 (2d Cir. 2011) (“ordinarily, expert medical opinion evidence is required, when the subject-matter to be inquired about is presumed not to be within common knowledge and experience”) (citation and quotation marks omitted) (applying New York law); Riegel v. Medtronic, Inc., 451 F.3d 104, 127 (2d Cir. 2006) (“because there was no competent evidence excluding [the defendant’s] proffered causes” of the plaintiffs’ injury after their expert was excluded, “there were no genuine issues of material fact for a jury on this claim”), aff’d, 552 U.S. 312 (2008); Washburn v. Merck & Co., 213 F.3d 627 (2d Cir. 2000) (affirming both expert exclusion and summary judgment) (applying New York law); Gidora v. Howmedica Osteonics Corp., 2019 WL 1129127, at *3 (S.D.N.Y. March 12, 2019) (“Where a claim raises complex issues requiring expert testimony to establish a fundamental element of the claim, summary judgment is appropriate if a plaintiff fails to produce a qualified expert or the plaintiff has been precluded from calling his or her proffered expert.”); Byrd v. Janssen Pharmaceuticals, Inc., 333 F. Supp.3d 111, 127-31 (N.D.N.Y. 2018) (judgment as a matter of law appropriate where plaintiff’s expert testimony failed to establish general causation); Adeghe v. Janssen Pharmaceuticals, Inc., 2018 WL 4112815, at *3 (S.D.N.Y. Aug. 29, 2018) (“because of the complex chemistry and biology involved in assessing the design of [the drug] and its alternatives, expert testimony is necessary”); Coleson v. Janssen Pharmaceutical, Inc., 251 F. Supp.3d 716, 723 (S.D.N.Y. 2017) (“Without competent medical expert testimony on the issue of causation, a jury would be left only to theorize as to how Plaintiff came to suffer from” his claimed injuries); Vargas v. Ortho-McNeil Pharmaceutical, Inc., 2013 WL 3776628, at *4 (N.D. Ohio July 17, 2013) (“It is clear that the determination of causation in this case requires the testimony of medical experts, which Plaintiff has repeatedly failed to provide.”) (applying New York law); In re Trasylol Products Liability Litigation, 2013 WL 1343529, at *13 (S.D. Fla. April 2, 2013) (after experts are excluded, all plaintiff’s claims “must fail”) (applying New York law); Dolphin v. Synthes (USA) Ltd., 2012 WL 13059723, at *3 (S.D.N.Y. Feb. 16, 2012) (“in cases that concern more complicated medical procedures, a jury cannot reasonably be expected to infer issues of causation and a medical expert is required”) (citing Fane); Maxwell v. Howmedica Osteonics Corp., 713 F. Supp.2d 84, 91 (N.D.N.Y. 2010) (“under New York law, a plaintiff seeking to establish a design defect is required to provide expert testimony as to the feasibility and efficacy of alternative designs”); Nealy v. U.S. Surgical Corp., 587 F. Supp.2d 579, 586 (S.D.N.Y. 2008) (“Expert medical opinion evidence is usually required to show the cause of an injury or disease because the medical effect on the human system of the infliction of injuries is generally not within the sphere of the common knowledge of the lay person.”); Rodriguez v. Mallinckrodt, Inc., 2007 WL 2811061, at *3 (E.D. Mo. Sept. 24, 2007) (“expert medical opinion evidence is required when the subject matter at issue is presumed to be beyond the common knowledge and experience of a jury”) (applying New York law), aff’d, 316 F. Appx. 527 (8th Cir. 2009); Prohaska v. Sofamor, S.N.C., 138 F. Supp.2d 422, 445 (W.D.N.Y. 2001) (“Absent competent medical expert testimony on the issue of causation, plaintiffs cannot prove the elements of a cause of action based in strict products liability or negligence.”); McLellan v. Sofamor-Danek Group, Inc., 1999 WL 222591, at *4 (W.D.N.Y. April 12, 1999) (“When competent medical opinion evidence is required, a judgment as a matter of law is appropriate if the plaintiff fails to adduce such.”) (citing Fane); Saari v. Merck & Co., 961 F. Supp. 387, 392 (N.D.N.Y. 1997) (“in a case such as this where there are complex medical issues, in order for plaintiff to prove that her alleged injuries were caused by defendants’ products, she must introduce expert medical testimony establishing causation”); Krasnopolsky v. Warner-Lambert Co., 799 F. Supp. 1342, 1348 (E.D.N.Y. 1992) (plaintiffs “have failed to submit any type of expert proof, in an affidavit or otherwise, which would establish any causation between [the] injury and the alleged negligence”); McGovern v. Davol, Inc., 2018 WL 1384549, at *7 (N.Y. Sup. March 15, 2018) (“Plaintiff fails to provide a medical expert who could opine that such a [product] defect was a substantial factor in causing Plaintiff’s injury”); Gentile v. Biogen Idec, Inc., 2016 WL 4168942, at *7 (Mass. Super. July 28, 2016) (“Because the adequacy of the warnings cannot be evaluated by a layperson, expert testimony is necessary to resolve the issue.”) (citation omitted) (applying New York law).

North Carolina

In North Carolina “cases involving complicated medical questions far removed from the ordinary experience and knowledge of laymen, only an expert can give competent opinion evidence as to the cause of the injury.”  Holley v. ACTS, Inc., 581 S.E.2d 750, 753 (N.C. 2003).  See Click v. Pilot Freight Carriers, Inc., 265 S.E.2d 389, 391 (N.C. 1980) (same as to the “exact nature and probable genesis of a particular type of injury”).

Due to the complexities of medical science, particularly with respect to diagnosis, methodology and determinations of causation, this Court has held that where the exact nature and probable genesis of a particular type of injury involves complicated medical questions far removed from the ordinary experience and knowledge of laymen, only an expert can give competent opinion evidence as to the cause of the injury.

Young v. Hickory Business Furniture, 538 S.E.2d 912, 915 (N.C. 2000) (citations and quotation marks omitted).  See Campbell v. Duke University Health Systems, Inc., 691 S.E.2d 31, 36 (N.C. App. 2010) (same standards applicable to civil suits); Freeman v. Blue Ridge Paper Products, Inc., 529 F. Appx. 719, 725 (6th Cir. 2013) (“the subject matter of causation in this case is far removed from the ordinary person’s experience, and the matter more closely parallels those cases in which North Carolina courts require expert proof of causation”) (citation omitted) (applying North Carolina law); Free v. Baker, 469 F. Appx. 786, 791 (11th Cir. 2012) (“Expert testimony is required to establish medical causation under North Carolina law.”) (applying North Carolina law); Riggins v. SSC Yanceyville Operating Co., LLC, 2018 WL 4374929, at *3 (M.D.N.C. Sept. 13, 2018)  (“In North Carolina, not only does a plaintiff establish the standard of care with expert testimony, but medical experts are relied upon to show medical causation”) (citation and quotation marks omitted); Phillip v. GEO Group, Inc., 2012 WL 5392120, at *7 (E.D.N.C. Nov. 5, 2012) (“North Carolina courts have applied the requirement for expert medical testimony to actions in which a party claims to have been injured by an airborne toxin”), aff’d, 520 F. Appx. 215 (4th Cir. 2013) (on basis of district court opinion); Butler v. United States, 2011 WL 5191701, at *5 (Mag. M.D.N.C. Aug. 2, 2011) (“where the injury is complicated or unusual, a plaintiff must present expert witness testimony”), adopted, 2011 WL 5170015 (M.D.N.C. Oct. 31, 2011), aff’d, 702 F.3d 749 (4th Cir. 2012); Fontenot v. TASER International, Inc., 2011 WL 2535016, at *8 (W.D.N.C. June 27, 2011) (“In a complex product liability case such as this, a plaintiff must present expert medical testimony to establish causation.”).

Thus, “[i]n North Carolina, a jury award [in a products liability case] cannot be sustained in the absence of expert medical testimony on the issue of causation.”  Hensley v. Danek Medical, Inc., 32 F. Supp.2d 345, 350 (W.D.N.C. 1998).  “Without admissible expert testimony on the issue of specific causation, [plaintiff] cannot prove his claims under North Carolina law.”  In re Testosterone Replacement Therapy Products Liability Litigation Coordinated Pretrial Proceedings, 2017 WL 1833173, at *22 (N.D. Ill. May 8, 2017), reconsideration denied, 2017 WL 2953703 (N.D. Ill. July 11, 2017) (applying North Carolina law).  See Blackmon v. G.UB.MK Constructors, 2016 WL 8674646, at *3 (E.D.N.C. Nov. 11, 2016) (“Without competent expert testimony, evidence of causation remains mere speculation or conjecture and summary judgment in favor of the defendant is appropriate.”) (citation and quotation marks omitted); Ward v. Ortho-McNeil Pharmaceutical, 2015 WL 4110990, at *4 (E.D.N.C. July 7, 2015) (“in cases involving complicated medical questions . . ., only an expert can give competent opinion evidence as to the cause of the injury”) (citation and quotation marks omitted); Lipscomb v. Orkin, Inc., 2014 WL 3510117, at *2 (E.D.N.C. July 14, 2014) (“where a layman can have no well-founded knowledge and can do no more than indulge in mere speculation (as to the cause of a physical condition), there is no proper foundation for a finding by the trier without expert medical testimony”) (citation and quotation marks omitted); Doe v. Ortho-Clinical Diagnostics, Inc., 440 F. Supp.2d 465, 478 (M.D.N.C. 2006) (“Given the Court’s ruling above excluding . . . Plaintiffs’ sole expert on both general and specific causation, Plaintiffs cannot meet their burden of proof on the essential element of causation.”); Dunn v. Sandoz Pharmaceuticals Corp., 275 F. Supp.2d 672, 684 (M.D.N.C. 2003) (entering summary judgment after exclusion of expert left plaintiff unable to prove causation); Ward v. American Medical Systems, Inc., 170 F. Supp.2d 594, 599 (W.D.N.C. 2001) (“a plaintiff is obligated to come forward with expert medical opinion that his medical problems were caused by the defective product”), aff’d, 38 F. Appx. 909 (4th Cir. 2002); Baraukas v. Danek Medical, Inc., 2000 WL 223508, at *3 (M.D.N.C. Jan. 13, 2000) (“Given plaintiffs’ failure to present expert medical testimony on causation . . ., this Court finds that summary judgment for defendants is appropriate.”); Driggers v. Sofamor, S.N.C., 44 F. Supp.2d 760, 764-65 (M.D.N.C. 1998) (“where the injury is complicated, . . . expert medical testimony on the issue of causation must be provided to support a jury award”).

North Dakota

North Dakota cases hold that “expert testimony is required if the issue is beyond the area of common knowledge or lay comprehension, or the issue is not within the ordinary experience of the jurors.”  Klimple v. Bahl, 727 N.W.2d 256, 259 (N.D. 2007) (quoting Leno v. Ehli, 339 N.W.2d 92, 99 (N.D. 1983)).  “[W]hen the causal relationship between a condition affecting the human body and a [defendant’s conduct] is not a matter within the common knowledge or comprehension of a layperson, the party bearing the burden of proof must present expert medical testimony establishing that relationship.”  Halvorson v. Sentry Insurance, 757 N.W.2d 398, 400 (N.D. 2008).  “[A] technical procedure requir[es] an expert witness to establish . . . a causal relationship between the violation and the harm complained of.”  Cartwright v. Tong, 896 N.W.2d 638, 643 (N.D. 2017).

Thus, “[i]n a toxic tort case, a reasonable estimate of exposure by a reliable expert is often the only way a plaintiff can prove specific causation.”  Otto v. Newfield Exploration Co., 2016 WL 7439585, at *3 (D. Mont. Dec. 22, 2016) (applying North Dakota law).

Ohio

“Expert testimony is needed” in Ohio “on complex issues outside the area of common knowledge, such as an injury’s cause and effect.”  Lederer v. St. Rita’s Medical Center, 702 N.E.2d. 476, 483 (Ohio 1997).

“Except as to questions of cause and effect which are so apparent as to be matters of common knowledge, the issue of causal connection between an injury and a specific subsequent physical disability involves a scientific inquiry and must be established by the opinion of medical witnesses competent to express such opinion. . . .  Establishing general causation and specific causation in cases involving exposure to . . . toxic substances involves a scientific inquiry, and thus causation must be established by the testimony of a medical expert.

Terry v. Caputo, 875 N.E.2d 72, 77 (Ohio 2007) (citation and quotation marks omitted) (emphasis original).  See Richards v. Copes-Vulcan, Inc., ___ A.3d ___, 2019 WL 3282056, at *5 (Del. July 22, 2019) (“Under Ohio law, . . . expert medical evidence is required to support specific causation.”) (applying Ohio law).  “The development of a medical condition is typically not within the knowledge of a layperson, thus requiring a medical expert to establish causation of the medical condition.”  Lloyd v. Rogerson, 2019 WL 2721413, at *7 (Ohio App. June 28, 2019) (citation omitted).

In a toxic-tort case, as here, the plaintiff must establish both general and specific causation. . . .  Both causation inquiries involve scientific assessments that must be established through the testimony of a medical expert.  Without this testimony, a plaintiff’s toxic tort claim will fail.

Pluck v. BP Oil Pipeline Co., 640 F.3d 671, 676-77 (6th Cir. 2011) (applying Ohio law).  See Viars v. Ironton, 2016 WL 3670171, at *9 (Ohio App. July 6, 2016) (‘Expert testimony is required to establish general causation and specific causation in cases [where] . . . the determination involves a scientific inquiry into matters beyond the knowledge or experience possessed by lay persons”); Davie v. Nationwide Mutual Insurance Co., 2015 WL 179287, at *4 (Ohio App. Jan. 15, 2015) (“With [plaintiff] failing to offer expert testimony at trial on whether his soft tissue injuries were proximately caused by the tortfeasor’s negligence, the court had no choice but to direct a verdict.”); Bogner v. Titleist Club, L.L.C., 2006 WL 3825228, at *2 (Ohio App. Dec. 29, 2006) (“Expert testimony is needed on complex issues outside the area of the laypersons common knowledge, such as an injury’s cause and effect.”) (citations omitted); Alden v. Phifer Wire Products, Inc., 2005 WL 1407776, at *3 (Ohio App. June 16, 2005) (affirming summary judgment; following Valentine); Valentine v. PPG Industries, Inc., 821 N.E.2d 580, 588 (Ohio App. 2004) (affirming summary judgment because “[t]o prove the proximate cause of a medical condition . . . expert medical testimony ordinarily is necessary”), aff’d, 850 N.E.2d 683 (Ohio 2006); Prysock v. Bahner, 2004 WL 1445565, at *2 (Ohio App. June 29, 2004) (“[e]xpert medical testimony is necessary to show an injury’s cause and effect”); Thompson I.G., LLC v. Edgetech I.G. Inc., 590 F. Appx. 532, 538 (6th Cir. 2014) (“the causation issues here are too complex for the jury to decide without the help of expert testimony”) (applying Ohio law); Madej v. Maiden, 2018 WL 5045768, at *4 (S.D. Ohio Oct. 17, 2018) (“Without expert medical testimony on both general causation and specific causation, a plaintiff’s toxic tort claim will fail”) (quoting Baker); Baker v. Chevron USA, Inc., 680 F. Supp.2d 865, 874 (S.D. Ohio 2010) (following Terry), aff’d, 533 F. Appx. 509 (6th Cir. 2013); Davison v. Cole Sewell Corp., 2006 WL 2129803, at *5 (S.D. Ohio July 28, 2006) (granting summary judgment where plaintiff failed “to establish causation through expert opinion.”), aff’d, 231 F. Appx. 444 (6th Cir. 2007); Day v. NLO, 851 F. Supp. 869, 881 (S.D. Ohio 1994) (medical monitoring claim requires plaintiffs “to show by expert medical testimony that they have increased risk of disease”).

The same considerations control in product liability.  “Ohio law requires expert testimony where aspects of the defect or the proposed alternative designs are technically complex and outside the understanding of a lay juror.”  Newell Rubbermaid, Inc. v. Raymond Corp., 676 F.3d 521, 529 (6th Cir. 2012) (applying Ohio law).  Likewise, in Ohio, “[w]hen a plaintiff alleges that the warning given to a prescribing physician is inadequate, the plaintiff must prove his claim through expert medical testimony.”  Graham v. American Cyanamid Co., 350 F.3d 496, 514 (6th Cir. 2003) (applying Ohio law).  Further, “[u]nder Ohio law, a plaintiff must present expert medical testimony to establish causation when she asserts a specific physical injury, the cause for which is not within common knowledge.”  Botnick v. Zimmer, Inc., 484 F. Supp.2d 715, 724 (N.D. Ohio 2007).

[W]hether a prescription drug is defective and whether it is the proximate cause of an injury are questions which lie outside the knowledge of lay witnesses.  Accordingly, [plaintiff] would have to introduce expert testimony to establish these elements of her claim.

Kerpelis v. Pfizer, Inc., 2004 WL 1326771, at *5 (Ohio App. June 7, 2004).  See Jones v. Roche Laboratories, 616 N.E.2d 545, 548 (Ohio App. 1992) (“expert opinion evidence is necessary for that [inadequate warning] showing”); Taylor v. Medtronics, Inc., 861 F.2d 980, 987-88 (6th Cir. 1988) (affirming summary judgment entered after plaintiff’s expert stricken) (applying Ohio law); Parillo v. Lowe’s Home Centers, LLC, 2017 WL 4124585, at *1 (S.D. Ohio Sept. 18, 2017) (“lay witness opinions regarding the cause of complex medical conditions are . . . irrelevant in a product liability lawsuit”); Z.H. v. Abbott Laboratories, Inc., 2016 WL 5661582, at *4 (N.D. Ohio Sept. 30, 2016) (“Defendants would still be entitled to summary judgment on Plaintiffs’ defective design claim because Plaintiffs offered no expert testimony that [the drug’s] formulation’s risks outweigh its benefits.”); Schmiedebusch v. Mallinckrodt, Inc., 2011 WL 5362066, at *4 (Mag. N.D. Ohio Sept. 13, 2011) (“Under Ohio law, expert medical testimony is required to establish causation of a specific physical injury, if such cause is not within common knowledge.”), adopted, 2011 WL 5362061 (N.D. Ohio Oct. 31, 2011); Utz v. Howmedica Osteonics Corp., 2009 WL 5409046, at *10 (N.D. Ohio March 31, 2009) (“Plaintiffs have failed to proffer expert testimony or other evidence to support this design defect theory.  Accordingly, summary judgment is granted in Defendants’ favor on this claim.”); Saraney v. TAP Pharmaceutical Products, Inc., 2007 WL 148845, at *6 n.3 (N.D. Ohio Jan. 16, 2007) (“The lack of an expert witness proves fatal to [plaintiffs’] product defect claims”); Yanovich v. Sulzer Orthopedics, Inc., 2006 WL 3716812, at *6 (N.D. Ohio Dec. 14, 2006) (summary judgment “warranted on all of plaintiffs’ claims” where plaintiffs had no “expert medical evidence showing that [plaintiff] was injured as a proximate result of the defect” in medical device); Grant v. Memry Corp., 2006 WL 2794732, at *6 (N.D. Ohio Sept. 27, 2006) (“the workings of a [medical device] and the causal relationship between a malfunctioning [medical device] and [plaintiff’s] physical injury are beyond the knowledge and understanding of laypersons, and therefore expert evidence is necessary”); Harmon v. American Red Cross, 2003 WL 22999468, at *1 (N.D. Ohio Dec. 17, 2003)  (“neither [plaintiff’s medical condition] nor what causes that condition is a matter of common knowledge. That being so, plaintiff must provide expert testimony in order to prevail. She not having done so, defendant is entitled to summary judgment.”).

Oklahoma

Under Oklahoma law, “[w]hen an injury is of a nature requiring a skilled and professional person to determine cause and the extent thereof, the scientific question presented must necessarily be determined by testimony of skilled and professional persons.”  Christian v. Gray, 65 P.3d 591, 601-02 (Okla. 2003) (quoting Williams v. Safeway Stores, Inc., 515 P.2d 223, 227 (Okla. 1973)).  The cause of an illness “is a matter of medical science to be established by expert testimony.”  Ruland v. Zenith Construction, 283 P.2d 540, 541 (Okla. 1955)).

In product liability and toxic tort cases as well, “Oklahoma law generally requires expert testimony for complex issues of medical causation.”  Hall v. Conoco, Inc., 886 F.3d 1308, 1317 (10th Cir. 2018) (applying Oklahoma law).

Where, as here, the effect of a defect in a [product] on the human body involved complex medical and biomechanical questions that are beyond a jury’s ordinary knowledge and common experience, expert witness testimony was the best evidence of general causation.  Without such evidence, a jury would have to speculate whether a design defect in the [product] caused or exacerbated [plaintiff’s] injuries.  Such speculation would be error.

Nash v. General Motors Corp., 153 P.3d 73, 75 (Okla. Civ. App. 2007).  See Rodgers v. Beechcraft Corp., 759 F. Appx. 646, 679 (10th Cir. 2018) (“In the context of a complicated [product], Plaintiffs needed expert testimony to prove causation.”) (applying Oklahoma law); Ortiz v. Cooper Tire & Rubber Co., 2015 WL 1498713, at *3 (W.D. Okla. March 31, 2015) (summary judgment granted against warning claim for lack of expert testimony); Carver v. Kia Motors Corp., 2012 WL 119587, at *6 (N.D. Okla. Jan. 12, 2012). (“Without expert testimony . . ., the question of whether [plaintiff’s] injuries were caused by the alleged defect . . . is far too speculative to present to a jury.”).

The same is of course true in prescription medical product liability litigation.  “[U]nder Oklahoma law, a plaintiff must introduce expert testimony if the fact in issue is not within the realm of ordinary experience of mankind.”  Hollander v. Sandoz Pharmaceutical Corp., 289 F.3d 1193, 1214 (10th Cir. 2002) (citation and quotation marks omitted) (applying Oklahoma law).

[P]laintiff is claiming that a complex medical device was defective and she has not identified an expert who will testify in support of her claims.  Expert testimony is essential in cases “[w]here injuries are of a character requiring skilled and professional men to determine the cause and extent thereof.”  Plaintiff alleges that the Device . . . caused her to suffer pain and long term injury, and this is the type of claim that must be supported by expert testimony.

Stewart v. Sulzer Orthopedics, Inc., 2011 WL 2491593, at *4 (N.D. Okla. June 22, 2011) (quoting Alexander v. Smith & Nephew, P.L.C., 98 F. Supp.2d 1276, 1284 (N.D. Okla. 2000)).  See Manous v. Mylan Pharmaceuticals, Inc., 982 F. Supp.2d 1282, 1285 (W.D. Okla. 2013) (summary judgment granted; “there is simply no such expert testimony” about defect or causation); Shrum v. Novartis Pharmaceuticals Corp., 2013 WL 3326645, at *2 (W.D. Okla. June 28, 2013) (“to meet [plaintiff’s] burden of proof on case-specific causation, she must proffer expert testimony on the issue”); Delano v. Smith & Nephew, Inc., 2000 WL 689692, at *1 (Okla. Dist. May 12, 2000) (“A plaintiff must bridge the gap from the [device’s] mechanical behavior to plaintiff’s symptoms with reliable and relevant expert medical causation testimony.”) (citation and quotation marks omitted).

Oregon

In Oregon, “[i]f the issue turns upon some fact beyond the ken of laymen, expert testimony must be produced.”  State v. Davis, 261 P.3d 1197, 1209 n.11 (Or. 2011) (citation and quotation marks omitted).  The “settled rule” is that “where injuries complained of are of such character as to require skilled and professional persons to determine the cause and extent thereof, the question is one of science and must necessarily be determined by testimony of skilled, professional persons.”  Cleland v. Wilcox, 543 P.2d 1032, 1034 (Or. 1975) (quoting Uris v. Compensation Department, 427 P.2d 753, 755 (Or. 1967)).

When the element of causation involves a complex medical question, as a matter of law, no rational juror can find that a plaintiff has established causation unless the plaintiff has presented expert testimony that there is a reasonable medical probability that the alleged negligence caused the plaintiff’s injuries.  The rule prevents jurors from speculating about causation in cases where that determination requires expertise beyond the knowledge and experience of an ordinary lay person.

Pinkerton v. Tri-County Metropolitan Service Dist., 125 P.3d 840, 843 (Or. App. 2005) (citations and quotation marks omitted).  “[W]hether plaintiff was required to present expert testimony “ is “a question of law.”  Vandermay v. Clayton, 984 P.2d 272, 277 (Or. 1999).

“This rule is frequently invoked in negligence cases involving medical causation.”  PacifiCorp v. Northwest Pipeline GP, 879 F. Supp.2d 1171, 1200 (D. Or. 2012).  See Thorson v. Bend Memorial Clinic, 419 P.3d 756, 759 (Or. App. 2018) (plaintiff lacked “the necessary expert testimony in order to avoid summary judgment”); Joshi v. Providence Health Systems Corp., 108 P.3d 1195, 1196 (Or. App. 2005), (“when causation involves a complex medical question, evidence is insufficient to go to the jury without expert testimony”), aff’d, 149 P.3d 1164 (Or. 2006); Chouinard v. Health Ventures, 39 P.3d 951, 954 (Or. App. 2002)  (in case involving “tumors and their effects on the body . . . the issue of causation was a complex medical question that required expert testimony”); Cook v. United Airlines, Inc., 379 F. Appx. 554, 555 (9th Cir. 2010) (“[u]nder Oregon law, [plaintiff] was required to present some expert evidence” of causation) (applying Oregon law).

Similarly, product liability and toxic tort cases require expert testimony on various issues to establish a plaintiff’s prima facie case.  “Under Oregon law, when the element of causation involves a complex medical question, a plaintiff must present expert testimony that there is a reasonable medical probability of causation.”  Phelps v. Wyeth, Inc., 938 F. Supp.2d 1055, 1068 (D. Or. 2013) (citation omitted).

[P]laintiffs must present evidence of both general and specific causation to prevail on their claims. . . .  Thus, plaintiffs must present expert testimony to show by a preponderance of the evidence that [use of the device] can and did cause plaintiffs’ [injury].

McClellan v. I-Flow Corp., 710 F. Supp.2d 1092, 1098 (D. Or. 2010).  See McDowell v. Allied Building Products Corp., 230 P.3d 552, 557 (Or. App. 2010) (affirming dismissal of asbestos case when plaintiff did not produce “prima facie expert proof of causation”); Teater v. Pfizer, Inc., 2013 WL 2455995, at *5 (D. Or. June 6, 2013) (“When, as here, “the element of causation involves a complex medical question, as a matter of law, no rational juror can find that a plaintiff has established causation unless the plaintiff has presented expert testimony. . . that the actions complained of caused the plaintiff’s injuries.”) (citation and quotation marks omitted) (emphasis original); Lusch v. Matrixx Initiatives, Inc., 2007 WL 2816203, at *7 (D. Or. Sept. 25, 2007) (“without expert testimony, plaintiff is similarly unable to create a genuine issue of material fact as to causation”); Rietcheck v. City of Arlington, 2006 WL 1371650, at *3 (D. Or. May 15, 2006) (“[t]he issue of causation concerning exposure to hazardous substances . . . involves a complex medical question” requiring expert testimony).