In trials across the country, juries have answered the scientific question: Did Johnson & Johnson’s baby powder cause women to get ovarian cancer?

Lawyers on both sides of the lawsuits have enlisted an army of experts to help jurors answer that question, but, so far, rulings addressing the admissibility of their opinions have been largely limited to state courts in Missouri, California, New Jersey and Georgia. Those rulings, however, appeared in briefs filed before U.S. District Judge Freda Wolfson ahead of a hearing this week featuring testimony from eight of the 39 expert witnesses designated for the first trials in the multidistrict litigation over Johnson & Johnson’s baby powder. That MDL now totals more than 12,600 lawsuits.