On Monday, “the Supreme Court unanimously rejected two challenges to the constitutionality of so-called ‘faithless elector’ laws, which penalize or remove presidential electors who fail to vote for the candidate they have pledged to support.” SCOTUSblog

Both sides support the decision:

“Perhaps in past cycles, a stronger sense of duty and honor prompted electors to keep their word, no matter how they personally felt about the winning candidate. In today’s more narcissistic culture, perhaps some addle-minded electors see changing their vote as a step to fame. The 2016 election saw seven faithless electors…

“Perhaps this year all the electors will take their duties seriously, and the trend of faithless electors will wane. But the unanimous decision probably increases the odds that electors will recognize that no message justifies breaking their promise. Justice Elena Kagan wrote in her majority opinion that states may instruct, ‘electors that they have no ground for reversing the vote of millions of its citizens . . . That direction accords with the Constitution — as well as with the trust of a Nation that here, We the People rule.’ How often do we get to say, ‘Amen, Justice Kagan’?”
Jim Geraghty, National Review

“In the very first contested election — the 1796 election between Federalist John Adams and Republican Thomas Jefferson — ‘would-be electors declared themselves for one or the other party’s presidential candidate,’ Kagan writes. By 1833, Justice Joseph Story wrote that ‘‘the electors are now chosen wholly with reference to particular candidates,’ having either ‘silently’ or ‘publicly pledge[d]’ how they will vote.’…

“In total, Kagan notes, only 180 faithless electoral votes have been cast in American history, out of more than 23,000 total votes cast. And a third of these were cast in the 1872 election, ‘when the Democratic Party’s nominee (Horace Greeley) died just after Election Day.’ Setting aside the 1872 election, ‘faithless votes represent just one-half of one percent of the total.’ This history, combined with Kagan’s textual analysis, is sufficient reason to allow states to sanction faithless electors.”
Ian Millhiser, Vox

“Justice Joseph Story was an early and authoritative source on American constitutional law. In 1833 he wrote that any ‘exercise of an independent judgment [by electors] would be treated as a political usurpation, dishonourable to the individual, and a fraud upon his constituents’… this result is faithful to the text of the Constitution and avoids creating chaos if all states had to allow their electors to act as free agents. After all, while chaos might make for compelling television, it makes for terrible governance.”
Zack Smith, Daily Signal

“The decision is important because it will help avoid an election disaster in which a few electors try to thwart the will of the people. More fundamentally, the decision shows that the Supreme Court is recognizing that presidential elections really are supposed to be about majoritarian democracy, notwithstanding the quirky and creaky features inherited from the men who wrote the Constitution over 230 years ago… When you have an old Constitution like ours, sometimes the best thing isn’t to buy a new one but to bring the old one into the shop and have expert mechanics do their best to help it run safely. Today the justices acted like good, skilled mechanics.”
Noah Feldman, Bloomberg

Other opinions below.