The Central District of California recently shut down, on preemption grounds, a group of class-action plaintiffs’ second attempt to assert claims alleging that benzoyl peroxide (BPO) in over-the-counter (OTC) acne treatments unavoidably degrades into the carcinogen benzene.

A cert petition filed in March in the long-running In re Fosamax (Alendronate Sodium) Products Liability Litigation gives the Supreme Court a chance to clarify—for the second time—the Third Circuit’s restrictive application of the impossibility preemption defense.