Supreme Court Justice Ketanji Brown Jackson said that a legal theory supported by the Republican National Committee in a case related to mail-in ballots “imperils a lot of different things.” Jackson noted during oral arguments in the case on Monday that election practices have changed over time, which she said undermines the idea that there was ever a consistent practice across all states. “It's been changing throughout the course in a way that undermines the notion that there was one consistent practice first of all, or that Congress's law, the meaning of Election Day in the federal statutes, somehow was...