A federal appeals court has reinstated litigation against a pharmaceutical company in a young man’s death, ruling a lower court had improperly excluded experts’ testimony.

Maxx Wendell, who died at age 21 in 2007 of hepatosplenic T-cell lymphoma, a very rare and aggressive cancer, had been treated for many years previously with a combination of drugs for inflammatory bowel disease, according to Friday’s ruling by the 9th U.S. Circuit Court of Appeals in San Francisco in Stephen Wendell; Lisa Wendell et al. v. GlaxoSmithKline L.L.C.; Teva Pharmaceuticals USA Inc.

Maxx’s parents filed suit in July 2009 against multiple drug manufacturers and distributors, asserting claims of negligence and strict liability, arguing the drugs he had been treated with for his disease had caused the cancer. After summary judgments and settlements, North Wales, Pennsylvania-based Teva was the sole remaining defendant.

In June 2014, the U.S. District Court in Oakland, California, granted Teva’s motion for summary judgment, ruling the testimony of two experts was unreliable and therefore inadmissible under federal rules of evidence.

On appeal, a three-judge panel of the 9th Circuit unanimously overturned the ruling. The District Court “ruled too narrowly at each individual consideration, without taking into account the broader picture of the experts’ overall mythology,” said the ruling. “It improperly ignored the experts’ experience, reliance on a variety of literature and studies, and review of Maxx’s medical records and history,” it said.

The experts were “highly qualified doctors” and “employed sound methodologies to reach their conclusions,” said the ruling. The District Court “was wrong to put so much weight on the fact that the experts’ opinions were not developed independently of litigation and had not been published.”

“While independent research into the topic at issue is helpful to establish reliability, its absence does not mean the experts’ methods were unreliable,” the ruling said.

The ruling said the District Court also incorrectly granted summary judgment to Teva on a duty to warn claim. “There is a genuine dispute of material fact” as to whether Maxx’s doctor’s conduct would have changed with warnings, said the panel, in remanding the case for further proceedings.