For a federal Court of Appeals to have jurisdiction over an interlocutory appeal under 28 USC 1292(b), the district court must first find that (a) there is a controlling question of law, (b) there are substantial grounds for difference of opinion on that question, and (c) immediate resolution of the question would materially advance the ultimate termination of the litigation.  In addition, the Court of Appeals must agree with those findings and exercise its discretion to accept the appeal.  Here, one of the two questions raised by the appeal–whether plaintiff had become a primary employer by becoming entwined with the primary employer’s activities–was a question of fact, not law and thus could not support an interlocutory appeal.  The other question was who bore the burden of proof on apportionment and divisibility of damages.  That was a question of law, but not one within the four corners of the appealed order denying a new trial, which did not reconsider the pretrial order assigning the burden of proof.  If the Court of Appeals had otherwise exercised jurisdiction over the appealed order, it could have considered questions raised by prior orders that were material to the appealed order, but here, the appealed order raised no issue appropriate for 1292(b) review and the earlier order could not fill that void.