Kamala Harris wants to talk about packing the Supreme Court.

Last Wednesday, during a video event hosted by the advocacy group Win With Black Women, the former vice president rattled off a long list of democracy reforms that could be part of an “expanded playbook” Democrats can use to reverse a series of recent policy losses, including the Republican Supreme Court’s recent decision repealing a 1982 amendment to the Voting Right Act.

Harris’s list included Puerto Rican and DC statehood, multimember congressional districts, a binding ethics code for Supreme Court justices, and a vague proposal to reform or eliminate the Electoral College. It also included “the idea of Supreme Court reform, which includes expanding the Supreme Court.”

Court-packing, or adding seats to a court in order to change its ideological or partisan makeup, was considered an exceedingly radical idea as recently as a decade ago. President Franklin D. Roosevelt proposed adding seats to the Supreme Court shortly after his landslide victory in the 1936 presidential election, but his proposal landed with a thud in Congress, and many historians blame Roosevelt’s court-packing plan for shattering the coalition that allowed him to enact the New Deal.

Since then, most US political leaders have approached the idea with trepidation. President Joe Biden tried to placate Democrats angered by the Republican Party’s dominance of the Supreme Court by appointing a toothless advisory commission. Harris inartfully tried to dance around the topic when it came up in her 2020 debate with former Vice President Mike Pence.

But the idea has grown increasingly mainstream in the past 10 years. In February, Utah Republicans packed their state supreme court after that court backed a challenge to the state’s GOP-friendly congressional maps. Republicans also added seats to the Georgia and Arizona supreme courts in 2016.

Democratic support for court-packing, meanwhile, has largely come from iconoclasts or from relatively obscure politicians seeking to break through onto the national stage. Pete Buttigieg, who at the time was a small-city mayor making a long-shot bid for the presidency, proposed a complicated plan in 2019 to create an ideologically balanced Court of 15 justices. Graham Platner, the Maine Democrat campaigning for US Senate on an anti-system message, also supports court-packing.

Harris, by contrast, is the Democratic Party’s most recent presidential nominee. So she is definitionally one of the central figures in the party’s establishment. The fact that she is now floating this most radical of Supreme Court reforms suggests that the idea is increasingly palatable to the Democratic center.

But is court-packing actually a good idea? One of court-packing’s primary benefits is that it is actually constitutional. Congress could add seats to the Supreme Court with ordinary legislation, while more moderate proposals, such as term limits for the justices, would almost certainly require a constitutional amendment.

But the fact that it is easy, at least as a constitutional matter, to pack the Court is also a reason to fear a future where court-packing is just an ordinary political tactic used by political parties that wish to gain control of the Supreme Court. If Democrats pack the Supreme Court in 2029, they almost certainly guarantee that Republicans will retaliate the next time the GOP controls Congress and the White House.

The Constitution does not say how many justices shall sit on the Supreme Court, and Congress changed the number several times in the past. The Judiciary Act of 1789 established a six-justice Court, and the Supreme Court briefly had 10 justices during the Lincoln administration.

If it had the votes, in other words, Congress could call for a 15-justice Court or even a 5,000-justice Court tomorrow, creating a whole raft of open seats that could be filled by the sitting president.

The same cannot be said about many less radical and more popular reforms. A recent YouGov poll, for example, found that nearly three-quarters of American adults support term limits for the justices. But the Constitution provides that Supreme Court justices “shall hold their offices during good behavior,” a provision that’s historically been understood to protect federal judges from removal unless they engage in serious misconduct. And, while some legal scholars and advocates have proposed ways to get around this provision, the constitutionality of a term limits law would ultimately be decided by the justices themselves — who obviously have a stake in preserving their own life tenure.

Similar problems arise from other proposals to reform the Court. Justice Samuel Alito, for example, claimed in 2023 that a law imposing an ethics code on the justices would be unconstitutional because “no provision in the Constitution gives [Congress] the authority to regulate the Supreme Court.”

He’s wrong. Article III of the Constitution says that the Supreme Court exercises appellate jurisdiction over most cases “under such Regulations as the Congress shall make.” But the text of the Constitution does not matter at all if five justices are willing to strike down a law regardless of what the Constitution says.

Of course, it’s possible to imagine the Supreme Court also attempting to strike down a court-packing bill. So, if Congress did ever decide to add seats to the Court, it would be wise to rapidly confirm the president’s nominees to prevent a judge from issuing an injunction before those new justices join the bench.

But even if the justices did attempt to block a court-packing bill, they’d have a tough time coming up with a legal argument, because there are so many historical examples where Congress changed the size of the Court.

The primary advantage of court-packing is that it would be difficult for the Court’s current majority to sabotage a court-packing law if it actually passed the Congress — once the Court was packed, the Republican justices who control it right now would become a powerless minority.

Realistically, however, the newly constituted Court would struggle to impose its will on red states and on other Republican Party power centers.

The enforcement crisis would become even more severe if a state refuses to comply with a Supreme Court order. States, after all, have their own police forces and other armed personnel who can resist federal authority. The South’s massive resistance campaign against Brown v. Board of Education (1954), the landmark school desegregation decision, largely succeeded for 10 years, until Congress passed legislation giving the federal government new tools to enforce that decision. Before Congress got involved, the federal government often had to send the military when it chose to enforce Brown against recalcitrant states.

Thus, if a packed Supreme Court attempts to reinstate Roe v. Wade in anti-abortion states, or if it requires those states to redraw their congressional maps to comply with the Voting Rights Act, the states could simply refuse. And, if the federal government tried to enforce the Court’s order, it would risk setting off a violent conflict with armed state forces.

Court-packing, in other words, would probably be effective if the goal were to prevent the Supreme Court from implementing more Republican Party policies from the bench. But it likely would not be effective if the goal were to impose Democratic policies on Republican states. A packed Court would have diminished legitimacy, and thus would likely have less ability to undo much of the current Court’s greatest damage or to replace the current Court’s right-leaning policies with a more liberal alternative.

The other danger is that, if Democrats do pack the Supreme Court, they better be confident that they will continue winning elections for the foreseeable future. Because if Republicans ever regain control of Congress and the White House, they can immediately repack the Court with enough justices like Samuel Alito to ensure that the Republicans never lose a federal court case ever again.

The price of packing the Court, in other words, is very high. That price might be worth paying if the Supreme Court is so hostile to voting rights and to the Democratic Party that Democrats risk being shut out of power forever unless they change the makeup of the Court. But a packed Court will be greatly diminished, and the very high risks of the plan backfiring are worth considering. Red states are unlikely to simply fall in line if a packed Court starts interfering with their election or abortion policies, even if all that this Court does is restore the same civil rights protections that used to exist until the Roberts Court came along.