The U.S. Court of Appeals for the Third Circuit has overturned the dismissal of multidistrict litigation over femur fractures suffered by users of Merck’s osteoporosis drug Fosamax. The decision gives new life to about 5,000 cases that have been dismissed in federal and state courts, according to plaintiffs’ counsel.

In the case, captioned In re Fosamax Products Liability Litigation, the appeals court vacated a decision below granting summary judgment to Merck on pre-emption grounds, finding the District Court misapplied the U.S. Supreme Court’s 2009 ruling in Wyeth v. Levine. In that case, the Supreme Court held that state-law failure-to-warn claims are pre-empted when there is clear evidence that the Food and Drug Administration would not have approved a warning label that the plaintiff claims was necessary.

In the Fosamax case, Third Circuit Judges Julio Fuentes, Michael Chagares and L. Felipe Restrepo said Merck failed to prove that it is entitled to the affirmative defense of pre-emption.

The appeals court said U.S. District Judge Joel Pisano erroneously granted summary judgment to Merck in June 2014 in a suit by Bernadette Glynn after wrongly concluding that the clear evidence standard had been met in that case. In 2009, the FDA rejected Merck’s proposed revision of language on the Fosamax label to warn of the potential danger of bone fractures. Pisano ruled that Glynn’s case was pre-empted because the FDA’s 2009 decision was “clear evidence that the FDA would not have approved a label change” prior to her injury. After that ruling was issued, Merck then was granted summary judgment on all cases stemming from injuries that occurred before September 2010, the date of a task force report linking Fosamax usage to femur fractures.

Courts have struggled with the “clear evidence” standard, which is “cryptic and open-ended,” Fuentes wrote for the court. The Fosamax case requires the court to address what “clear evidence” is and who should decide when it exists, he wrote. The panel wrote that “clear evidence” applies solely to the applicable standard of proof, and that the question of whether the FDA would have rejected a label change is a question for the jury and not a judge.

In 2013, Merck reached a separate settlement of $27 million with approximately 1,200 Fosamax users who suffered necrosis of the jawbone.

In the femur fracture litigation, the plaintiff’s lawyer, Paul Pennock of Weitz & Luxenberg in New York, said the appeals court “nailed what the court was saying in Wyeth—look, if the drug company comes in to the FDA, tells the FDA here’s the warning, and the FDA says no, we’re not putting that warning you have on the drug, the warning you have is good, then you’re federally pre-empted on failure to warn. In this instance, Merck came in with a warning. The FDA said we need a warning—women’s femurs are spontaneously breaking around the country, but this is not a warning,”

Pennock said Pisano erroneously concluded that a “convoluted and watered-down” label change proposed to the FDA by Merck was sufficient to win federal pre-emption for the company from state claims for failure to warn.

Merck issued a statement about the ruling through spokeswoman Lainie Keller.

“Merck remains confident in the efficacy and safety profile of Fosamax and will continue to always act in the best interest of patients. The company has continuously provided appropriate and timely information about Fosamax to consumers and to the medical, scientific, and regulatory communities,” the statement said.

“Merck believes the question of preemption is one for a court, not a jury to decide, and the company is therefore reviewing its options going forward. Merck continues to believe that it presented clear evidence that the FDA would not have allowed an AFF [Atypical Femur Fracture] Precaution in the Fosamax label prior to September 2010, and we remain fully committed to defending these cases,” the Merck statement said.