In the case of Chiafalo v. Washington, 2019, the U.S Supreme Court ruled that states have the right to enforce an elector's pledge in presidential elections. The case arose when three electors from Washington state voted contrary to their pledges in the 2016 Presidential Election; instead of voting for Hillary Clinton and Tim Kaine who won popular votes in their state, they casted their electoral votes for Colin Powell. As a result, they were fined $1,000 each under a law that penalizes "faithless" or unfaithful electors who do not vote according to their pledges. The faithless electors challenged this fine arguing it violated their constitutional rights as members of Electoral College but both lower courts upheld these fines leading them to appeal at Supreme Court level where justices unanimously affirmed lower court rulings stating that Constitution grants states authority over its own slate of presidential electors including power to sanction them if they break pledged vote.

In the dissenting opinion for CHIAFALO v. WASHINGTON, Justice Clarence Thomas argued that states have no power to enforce how electors vote because the Constitution does not explicitly grant them this authority. He contended that while states can appoint electors, they cannot control their votes once appointed. According to him, any attempt by a state to impose legal penalties on faithless electors would be unconstitutional interference with federal functions and violate principles of federalism. Furthermore, he disagreed with the majority's reliance on historical practices as evidence of constitutional meaning and instead emphasized textual interpretation over tradition or precedent in determining constitutionality.