It’s hard to think of any recent litigation where plaintiffs didn’t seek overblown discovery about adverse event reports and then have their experts rely on those reports in an effort to establish causation.  But as we’ve blogged about repeatedly, reports from the FDA’s Adverse Event Reporting System (“FAERS”) do not establish causation (and, for good measure, they don’t constitute newly acquired information). Today’s decision, Taylor v. Dixon, 2026 WL 865183 (M.D. Fla. Mar. 30, 2026), is a little different since it involves a federal habeas petition.  But we couldn’t resist blogging about it given the court’s comprehensive take-down of the attempted use of an adverse event report to show causation. 

First a little background. The plaintiff in Taylor was convicted in connection with allegations that she had Munchausen syndrome by proxy – a psychological disorder in which a person fabricates symptoms in her child to gain the attention of medical professionals.  A jury found plaintiff guilty in connection with poisoning her four-month-old child with iron drops and then seeking medical attention for the child at a Florida hospital. She was sentenced to 12 years in prison. After exhausting her appeals in the state courts, she filed a federal habeas action seeking post-conviction relief.

In support of her habeas petition, plaintiff provided FAERS excerpts which referred to the hospitalization of her child and, according to plaintiff, showed that the administration of the medication Buminate at the hospital caused the child’s increase in blood iron concentrations. Although the court held that it could not consider the FAERS report since it was not before the trial court, it provided a detailed analysis explaining that, if it did consider the report, it would not have altered the outcome of plaintiff’s conviction.

The court held that there was no “reasonable probability” that the FAERS information would have been admitted in the underlying trial, so it could not have changed the outcome. Id. at *18. The court based its holding on the fact that adverse event reports are not based on any scientific methodology, but are simply accounts of events that provide piecemeal, anecdotal information.  Adverse event reports are “generally considered one of the least reliable sources of support for a causation opinion” because of serious limitations:

The FDA reporting system itself also has several intrinsic limitations, including (1) uncertainty that the drug actually caused the reported event, since the FDA does not require that causation be proven before the adverse event data is reported; (2) insufficient detail from which to evaluate causation; (3) information in the reports is unverified and subject to a variety of reporting biases; and (4) the underlying data may be affected by reporting bias stemming from publicity or litigation.

Id. at *19 (quoting In re Abilify (Aripiprazole) Prods. Liab. Litig., 299 F. Supp. 3d 1291, 1310 (N.D. Fla. 2018)).  The existence of adverse event reports says nothing about whether the drug is causing the adverse events, and the reports themselves are excludable at trial both as hearsay and on the grounds that their probative value is substantially outweighed by the danger of unfair prejudice. The FAERS report in question would have properly been excluded as hearsay at trial.

If the report wasn’t excluded as hearsay, it was still “patently unreliable as proof of causation.” Id. at *20. The FDA received the FAERS report from the manufacturer, and the very duty imposed on manufacturers to report all adverse events underscores their unreliability:

[B]ecause the regulation imposes a broad duty on manufacturers to report adverse events, and to forward all adverse event reports received from providers and patients, a manufacture might reasonably consider itself bound to report an event to the FDA even when the manufacturer does not believe, and that the available information does not support, that its drug actually caused or contributed to the event.

Id. at *20 (citing 21 C.F.R. §§ 314.80(b), (c)(1), (l)). Thus, even if the report wasn’t excluded as hearsay, it “would have almost certainly been excluded as creating a danger of unfair prejudice under Rule 403.” Id.  

Aside from the adverse event argument, plaintiff raised 14 other grounds for relief in her habeas petition. None of those are relevant to our blog, but the court denied them all and dismissed her claims with prejudice.  So while this plaintiff serves her time, we’ll stash this decision in our toolbox to use the next time plaintiffs use adverse event reports in an attempt to establish causation.