Case Facts
The order is a Special Master Order filed September 3, 2025, in the multidistrict litigation captioned In re: Valsartan, Losartan, and Irbesartan Products Liability Litigation, MDL No. 2875, pending before Chief Judge Renée Marie Bumb in the U.S. District Court for the District of New Jersey, Camden Vicinage. It applies to the case brought by Gaston J. Roberts, Jr. and his wife, Jan Roberts, Case No. 1:20-cv-00946-RBK-JS. The order resolves a defense motion to exclude the opinions of plaintiffs’ expert, Dr. William Sawyer, after the Special Master, retired Third Circuit judge Thomas I. Vanaskie, considered the motion, the opposition and reply briefs, and the declarations and exhibits the parties filed in connection with it.
The Setup
The motion arose because Dr. Sawyer’s report cited sources that turned out not to exist. The order attributes this to Sawyer’s “use of an artificial intelligence tool without adequate verification of the sources generated by the artificial intelligence tool” - he had relied on an AI tool in preparing his report and had not confirmed that the citations it produced were real before submitting his opinions.
The Challenge
Defendants moved to exclude Sawyer’s opinions over the nonexistent citations. The Special Master did not dispute that the problem was real. But he found it went to Sawyer’s “failure to verify the sources cited in his report,” not to the reliability of his underlying methodology, which the order describes as “otherwise the product of reliable scientific methodology” and supported by “good grounds.” On that basis, the fabricated citations, standing alone, did not warrant excluding Sawyer’s opinions.
The Ruling
Special Master Vanaskie denied the motion to exclude Sawyer’s opinions outright. The order states that the citation problem, “while perhaps warranting an award of costs in favor the defense and permitting cross examination of Dr. Sawyer during the trial on his failure to verify the sources cited in his report, does not warrant exclusion of his opinions.” It grounds that conclusion in “the liberal thrust of the Federal Rules of Evidence, the flexible nature of the Daubert inquiry, and the proper roles of the judge and jury in evaluating the ultimate credibility of an expert’s opinion.” The order leaves open the possibility of a costs award against Sawyer’s side over the episode and expressly preserves the AI-citation issue for cross-examination at trial, treating it as a question for the jury’s assessment of credibility rather than a threshold bar to Sawyer testifying at all.
The Kicker
A report built in part on sources that do not exist survived a challenge to its admissibility because, in the Special Master’s view, the sources were beside the point - it was the methodology behind Sawyer’s opinions, not the accuracy of his citations, that decided whether he could testify.
What Was Alleged vs. What the Court Found
→ Alleged: Dr. Sawyer’s report cited sources that do not exist, generated by an AI tool he used without adequately verifying its output.
→ Found: the fabricated citations reflected a failure to verify sources, not a defect in Sawyer’s underlying scientific methodology, which the Special Master found reliable and supported by “good grounds.”
→ Ruling: the motion to exclude is denied; the AI-citation problem may instead support an award of costs to the defense and gives defendants grounds to cross-examine Sawyer at trial on his failure to verify his sources.
The Lesson
The order treats an AI-generated citation problem as separable from the reliability of an expert’s actual methodology. The fabricated sources became a costs-and-cross-examination issue rather than a reason to keep Sawyer off the stand, so long as the substance behind his opinions held up on its own.
Takeaways
If you’re retaining experts:
Verify every citation an AI tool produces before a report is filed. A court may treat unverified AI citations as a costs-and-credibility problem rather than an automatic bar to testifying, but that outcome depends on the underlying methodology holding up independently.
If you’re an expert:
The line the Special Master drew here was between sourcing and methodology — citations you can’t verify still leave you exposed to costs and cross-examination even where your opinions otherwise survive.
If you’re opposing counsel:
A citation-fabrication problem you can prove is not the same as an automatic exclusion; be ready to attack the underlying methodology directly rather than relying on the AI issue alone.
