ENDLESSLY CONTROVERSIAL, the unique American system of presidential election faces especially strong debate over its legitimacy today, in part because the 2016 presidential election resulted in a decisive electoral college victory for President Trump even though his opponent received 2.87 million more popular votes. Still, whatever one thinks about abolishing the electoral college, it will be in use for the 2020 election. There must be as little ambiguity as possible about the legal framework in which it operates, lest confusion and controversy further destabilize an already polarized and conflictual body politic. Fortunately, the Supreme Court has agreed to resolve one key source of uncertainty well in advance of the November election.

The issue in two cases the court agreed on Jan. 17 to hear — one from Washington state and one from Colorado — is whether individual members of the electoral college are free to vote for whomever they please, or whether states may pass laws requiring them to cast votes for the candidate to whom they pledged their votes prior to the election. Such laws exist in 29 states and the District, according to the National Conference of State Legislatures; they conform to the widespread public expectation, developed over centuries of common practice, that each state’s electoral votes will go to the winner of its popular vote — except for Maine and Nebraska, which award some by congressional district.

However, the notion of electors as free agents also has a credible historical foundation, in the framers’ original concept that electors be “capable of analyzing the qualities” of a good president, as Alexander Hamilton put it. Since 1796, 167 electors have voted, or attempted to vote, for candidates not backed by the voters of their states — 10 of them in 2016. Congress has generally accepted the votes of “faithless electors,” in part because there have never been enough of them to change the outcome. In light of today’s volatile polarization, and the likelihood of a close electoral vote in 2020, that particular constitutional loose end can no longer be left hanging.

In essence, the justices must choose between a formal reading of the Constitution and a pragmatic one. No phrase of the Constitution expressly limits electors’ independent judgment, and Hamilton’s words certainly suggest the framers expected them to use it. That was the basis upon which the Denver-based U.S. Court of Appeals for the 10th Circuit last year struck down Colorado’s attempt to punish a Hillary Clinton elector who tried to vote for Republican John Kasich. Nevertheless, the system has evolved differently in practice; also, the Constitution empowers states to “appoint” electors, which arguably includes the power to direct them to vote as pledged.

Washington’s supreme court relied on that reasoning to uphold a fine against three 2016 faithless electors — and on balance it was the right call. Voters have enough concerns about the legitimacy of the electoral college without adding the risk, however small, that individual electors might not follow the clear expectations of those who choose them. No doubt the political parties would take steps to guarantee the faithfulness of their electors if the Supreme Court granted the electors free agency. But we see no reason to forbid states from making that assurance double sure.

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