The U.S. Supreme Court hasn’t always had nine justices—it started with six, went briefly down to five, back to six, then seven, then nine, and, during the Civil War, ten. If Trump confirms a replacement for Ruth Bader Ginsburg and Democrats later regain the presidency and Senate, Democrats are threatening to change the number again.
The Constitution doesn’t specify that the Supreme Court needs to be a particular size. The founders “knew the country was going to grow,” says Mark Tushnet, a professor emeritus at Harvard Law School who serves on the advisory board of Take Back the Court, an organization that aims to reform the judiciary. “They didn’t want to saddle the Constitution with a particular formulation. They could design a court that would fit the country that they were living in. But they didn’t know what was going to happen in the future and wanted to leave it open.”
The current size of the Supreme Court has been in place since 1869. During the Great Depression, after the court repeatedly struck down New Deal legislation, Franklin D. Roosevelt proposed “packing the court” with more justices. “There’s a subsurface argument that’s going to surface soon that, in fact, since the failure of the court-packing plan in 1937, a kind of constitutional convention has been created that you can’t change the size of the court merely for political reasons,” Tushnet says. Still, he says that the standard legal opinion now is that the president and Congress can choose to change the number of justices at any time they want.