Even for a behemoth like Microsoft Corp., going head-to-head with the federal government at the U.S. Supreme Court is no small matter. Since its case over emails stored in Ireland began in 2013, the tech giant has rallied the support of the industry, law and computer science academics, and European Union lawmakers in arguing that a domestic warrant should not apply to data kept abroad. Now, the sides are gearing up for oral argument on Feb. 27.