The U.S. Court of Appeals for the Sixth Circuit made it clear that it’s the court’s purview, not a jury’s, to determine whether an expert’s testimony is “relevant and reliable” when it comes to issues such as causation. It gave that lesson Feb. 13 when it affirmed a lower court’s dismissal of multi-district litigation in which the plaintiffs claimed that Onglyza (saxagliptin) and Kombiglyze (saxagliptin/metformin hydrochloride), developed by Astrazeneca plc and Bristol Myers Squibb Co., caused their heart failure.