President Joe Biden has turned to a familiar Washington institution — the blue-ribbon commission — to try to defuse a political problem. Progressive activists have been pressing the president to support an enlargement of the Supreme Court — "court-packing" in Washington parlance.

Such a position would be a reversal for Biden, who in 2019 said: "I'm not prepared to go on and try to pack the court, because we'll live to rue that day."

The 36-member commission announced on Friday will look at "the merits and legality of particular reform proposals." That would include not only court-packing but also a proposal that justices serve lengthy fixed terms — an idea endorsed by the Los Angeles Times Editorial Board.

But to some progressives, court-packing is the only way to ensure that a majority of Republican-appointed justices won't thwart the agenda of Biden and a Democratic Congress.

There's also an element of revenge in the call for a larger court: Democrats are still fuming, understandably, about Sen. Mitch McConnell's refusal in 2016 to let the Senate consider President Barack Obama's nomination of Merrick Garland (now the U.S. Attorney General) to replace Justice Antonin Scalia, who had died unexpectedly.

McConnell argued that when a vacancy occurs in an election year, the American people "should have a voice in the selection of their next Supreme Court justice." McConnell blithely violated that invented principle in 2020 when the Republican-controlled Senate rushed to confirm President Donald Trump's election-year nomination of Judge Amy Coney Barrett.

Yet court-packing could set off a chain reaction of court enlargement every time the Senate and the White House changed hands. As Biden put it in 2019: "We had three justices. Next time around, we lose control, they add three justices. We begin to lose any credibility the court has at all."

That's not the only argument against court-packing.

In a speech last Tuesday at Harvard Law School, Justice Stephen Breyer — the court's senior Democratic appointee — suggested that advocates of court-packing and other structural changes in the court should "think long and hard before they embody those changes in law."

Breyer said that the court's authority relies on "a trust that the court is guided by legal principle, not politics." He then warned: "Structural alteration motivated by the perception of political influence can only feed that latter perception, further eroding that trust."

Breyer's comments were a variation of a now famous statement by Chief Justice John Roberts: "We do not have Obama judges or Trump judges, Bush judges or Clinton judges."

Roberts' description of a federal judiciary free of politics was too simple (as I wrote here). But the notion that the Supreme Court is a partisan body is also a distortion.

The Supreme Court — including three Trump appointees — didn't come to Trump's rescue when he and his allies contested the result of the election, a fact alluded to by Breyer.

Members of Biden's commission will hear from people who want to expand the court. They also should listen to Breyer.