Every young conservative judge that the GOP has stacked onto the federal courts amounts to a sandbag against that rising demographic wave. Trump’s nominations to the Supreme Court of Brett Kavanaugh, Neil Gorsuch, and Barrett—whom a slim majority of Republican senators appears determined to seat by Election Day—represent the capstone of that strategy. As the nation’s growing racial and religious diversity limits the GOP’s prospects, filling the courts with conservatives constitutes what the Princeton University historian Sean Wilentz calls “the right-wing firewall” against a country evolving electorally away from the party.

This dynamic suggests that the 2020s could reprise earlier conflicts in American history, when a Court majority nominated and confirmed by the dominant party of a previous era systematically blocked the agenda of a newly emerging political majority—with explosive consequences. That happened as far back as the first years of the 19th century, when electoral dominance tipped from John Adams and the Federalists to Thomas Jefferson and his Democratic-Republican Party. At the time—and in language today’s Democrats would recognize—Jefferson complained that the Federalists “have retreated into the judiciary as a stronghold … the tenure of which renders it difficult to dislodge them.”…

The result is a Republican Supreme Court majority that, to an unprecedented extent, embodies minority rule. Assuming Barrett is confirmed, five of the six sitting Republican justices will have been appointed by GOP presidents who initially lost the popular vote. (George W. Bush, like Trump, won the Electoral College and lost the popular vote in his first election.) And all three of Trump’s nominees will have been confirmed by senators who represented less than half of the American public. The same is true for Thomas, who was nominated by George H. W. Bush.