In 2020, as a candidate for president himself, Mr. Biden was forceful in his rejection of court packing. If Democrats expanded the number of justices, he said, they would “live to rue [the] day.” He painted a picture — just as Roosevelt’s critics did — of an endless cycle of retribution, with each round of court packing sparking another by the opposing party until “we begin to lose any credibility the court has at all.” It is a reasonable concern. Yet Mr. Biden has made clear his animus extends to other reforms, including term limits for justices. “It’s a lifetime appointment,” he said in 2020. “I’m not going to attempt to change that at all.”

He has been true to his word. Upon taking office, he created a commission to review proposals for court reform and then removed its teeth, asking the group to write a report containing no recommendations. When “staggered term limits” — the idea of setting an 18-year term for justices and mandating that two (and only two) appointments would be made during each four-year presidency — emerged as something close to a consensus solution, Mr. Biden shrugged it off without comment, leaving a bitter taste for many who had dedicated their time and insights to the effort.

Mr. Biden, the explanation goes, is an institutionalist. During his many years on the Judiciary Committee, he spoke of the Supreme Court with respect, even reverence. It has proved a hard habit to break, even as the court’s entrenched, amped-up supermajority wages its campaign against the 21st century (and much of the 20th). “His admiration for the court as an institution has been overtaken by reality,” Harvard Law School’s Laurence Tribe, who also served on the commission, told Politico last summer. “And I think it’s time to wake up.” Sometimes an institution must be saved from itself.

Popular discontent with the court is growing, for good reason, and will seek outlets for its expression. Mr. Biden might worry that by discussing the court, he will politicize the court. But as Justice Elena Kagan has pointed out, the court itself has already done that. And absent the president’s engagement, the loudest, angriest voices will fill the void. He has a window, for now, in which he might set the terms for a productive, not destructive, discussion about remedies — a discussion that will outlast his own time in office. Court reform is a long game. Ending life tenure for justices, for example, would likely require a constitutional amendment — a daunting prospect, but far from impossible if Mr. Biden gets to work in laying the groundwork. “The presidency,” Barack Obama has written, “is a relay race.”

Consider how we arrived at this moment. The radicalization of the Supreme Court seems to have hit like a sudden storm: In just four years, Donald Trump installed three new justices. But the right’s takeover of American law was set in motion in the late 1960s by Richard Nixon, who attacked the “creeping permissiveness” of liberal judges and expounded “strict constructionism.” Later Ronald Reagan, an even truer believer, carried the crusade into the 1980s — transforming the judiciary through his appointments and changing public attitudes by insisting that the framers’ “original intent” ran unerringly in the direction of smaller government. The path from Nixon to Reagan to Dobbs was half a century long.

“No matter how long the road,” Mr. Biden promised in Philadelphia, “progress does come.” Yet it will not come unless every American of conscience — including the one in the White House — steps off the sidelines. Until then, the assault on democracy he described will continue. It will be waged in state legislatures and in Congress, and on the first Monday of October it will recommence in the conference room of the Supreme Court.