Rheumatology ExpertA popcorn aficionado who was diagnosed with lung disease—which he claimed was caused by his eating numerous bags of microwave popcorn on a daily basis for several years—brought suit for breach of implied warranty against manufacturers. The popcorn’s butter flavoring contained diacetyl, which Plaintiff said caused his lung disease bronchiolitis obliterans. Defendant manufacturer presented evidence from a rheumatology expert who testified Plaintiff had rheumatoid arthritis.

Plaintiff ate one to three bags of microwave popcorn each day for 20 years and practiced “a ritual of slowly opening the freshly-popped bag as he breathed the aroma in through his nose.”

At trial, a number of expert witnesses agreed Plaintiff had bronchiolitis obliterans, but their opinions differed as to whether the condition was caused by diacetyl exposure or an unrelated autoimmune disease. One of the Plaintiff’s expert witnesses testified his bronchiolitis obliterans was caused by his inhalation of microwave popcorn fumes containing diacetyl. This medical expert acknowledged that he had written the only published article supporting the theory that consumers—as opposed to industrial workers—can get bronchiolitis obliterans from diacetyl. The article appeared in a journal he himself edited.

Prior to the testimony of the Defendant’s rheumatology expert, the parties disputed whether he had considered diacetyl in his differential diagnosis. The trial court permitted the rheumatology expert to testify to determine if Defendant could lay a proper foundation. The expert testified about articles that had never been provided to Plaintiff’s counsel, and an objection was raised by Plaintiff. After the jury was excused, the rheumatology expert admitted he had conducted additional research to prepare for trial—unbeknownst to Defendant’s counsel.

The district court limited his testimony to his disclosure report. The judge ordered that he not be questioned about the additional articles, and he was precluded from referring to them. The judge also told the expert, “…I know it’s virtually impossible, but you have to try and put them out of your head when you answer and try and answer as if it was before you read the articles. You know, it’s inhuman to ask that. All I can do is ask you to do the best you can.”

The rheumatology expert resumed his testimony before the jury and testified he hadn’t considered whether diacetyl had caused Plaintiff’s bronchiolitis obliterans because “he had enough criteria of a systemic autoimmune disease that whether or not he used popcorn was really irrelevant.” After his concession that he hadn’t done a proper differential diagnosis, the district court struck all of the rheumatologist’s testimony. The jury was instructed to disregard all of the expert’s testimony.

Following a jury verdict in favor of Defendant, Plaintiff moved for judgment as a matter of law or a new trial based on the rheumatologist’s stricken testimony and his admitted testimony. Plaintiff argued that the jury was improperly influenced by the expert’s testimony despite the judge’s limiting instructions, basing the assertion in part on juror interviews conducted after the trial. Plaintiff argued he was entitled to judgment as a matter of law because three elements of the breach of implied warranty claim weren’t disputed and shouldn’t have been submitted to the jury. The district court denied the motions, and Plaintiff appealed.

On appeal, Plaintiff argued that he was entitled to a new trial because the rheumatologist’s stricken testimony was prejudicial. Plaintiff contended the district judge’s curative instruction was insufficient because it told the jury to put the rheumatologist’s testimony out of their minds while at the same time admitting to them he knew it was impossible. Adding to the confusion, Plaintiff said that the trial judge declared that the expert had done nothing wrong. This, Plaintiff argued, gave the jury the impression that “the rheumatology expert was a saint whose only mistake was to continue researching on the topic beyond some arbitrary court-imposed deadline.” Plaintiff also claimed he was entitled to an evidentiary hearing because some jurors stated during post-trial interviews they had relied on the rheumatologist’s stricken testimony.

Chief Judge William J. Riley of the U.S. Court of Appeals for the Eighth Circuit, writing for the court, disagreed with Plaintiff’s claims. He explained that because Plaintiff didn’t object to the district court’s curative instruction regarding the rheumatologist’s testimony, he forfeited any error absent a showing of plain error—a “stringently limited” standard of review. The Chief Judge reasoned that the Court will “normally presume that a jury will follow an instruction to disregard inadmissible evidence inadvertently presented to it, unless there is an ‘overwhelming probability’ that the jury will be unable to follow the court’s instructions.”

The Chief Judge wrote that the appellate court wasn’t convinced there was “an overwhelming probability” the jury couldn’t follow the trial judge’s curative instruction. Although Plaintiff was technically correct that the rheumatology expert was the only witness to testify that Plaintiff had rheumatoid arthritis, the Chief Judge noted that three other witnesses were in substantial agreement that Plaintiff’s bronchiolitis obliterans was related to an autoimmune or rheumatoid process. Further, although what happened during the rheumatologist’s testimony was “perplexing,” the Chief Judge said the Court wasn’t persuaded it was an intentional attempt by defense counsel to put inadmissible evidence in front of the jury.

As a result, the Eighth Circuit held that overwhelming probability didn’t exist that jury couldn’t follow curative instruction to disregard stricken testimony by Defendant’s expert concerning causation. A new trial wasn’t warranted, and the judgment of the district court was affirmed.



Stults v. American Pop Corn Company, — F.3d —-, No. 14–3658, 2016 WL 853283 (Cir. 8 March 4, 2016).