Sen. Al Franken said Tuesday that he will use an arcane Senate tradition to try to derail one of President Trump’s appeals court nominees, marking an escalation in what has become a nasty fight over the shape of the federal judiciary. Mr. Franken said he won’t return his “blue slip” for Minnesota Supreme Court Justice David Stras, Mr. Trump’s nominee for the 8th U.S. Circuit Court of Appeals. Under Senate tradition, the chamber won’t proceed on a judicial nominee unless both home-state senators return their blue slips, signifying acquiescence in the pick. Left with little power to filibuster, the blue...