Who elects the president of the United States?

In a democracy, that shouldn’t be a trick question. Thanks to the Electoral College, it seems like one. The American people cast their ballots on a Tuesday in early November, but on a national level that vote is legally meaningless. The real election happens about six weeks later, when 538 presidential electors — most of them average citizens chosen by local party leaders — meet in their respective state capitals and cast their ballots.

Nearly always, the electors vote for the candidate who won the most popular votes in their state. But do they have to? That’s the question that the Supreme Court has agreed to answer in two related cases it will hear this spring. The cases — one from Colorado and one from Washington — raise an alarming prospect: Can presidential electors vote for whomever they please, disregarding what the voters of their state said?

More than 160 “faithless electors” have chosen to go this route since the nation’s founding, a tiny fraction of all electoral votes in history. But the issue has become freshly relevant because of a concerted effort to persuade dozens of Republican electors in 2016 to switch their votes to prevent Donald Trump from taking the White House. In the end, 10 electors voted or tried to vote for someone other than their state’s popular-vote winner — the most in a single election in more than a century. (In 1872, 63 electors went against their pledge to vote for Horace Greeley, the Liberal Republican candidate, but that was because Greeley died shortly after Election Day.)

Even though faithless electors have never come close to changing the outcome of an election, more than two dozen states have passed laws requiring their electors to vote for the state’s popular-vote winner. Some punish those who don’t, while others replace faithless electors with ones who will do the job they pledged to do.