Term limits for Supreme Court justices are a popular idea, but would require amending the Constitution and would be unlikely to affect the current justices, legal scholars say.

On Monday, President Biden endorsed term limits as one of “three bold reforms to restore trust and accountability” in the court.

Biden also called for a constitutional amendment to say former presidents have no immunity from criminal charges for their actions in the White House, which would reverse the Supreme Court’s decision in early July.

And he endorsed a “binding code of conduct” that applies to the Supreme Court justices.

Biden was less clear on how term limits could become law and whether they would apply only to new justices or instead force older justices into retirement.

“I support a system in which the president would appoint a justice every two years to spend 18 years in active service on the Supreme Court,” Biden said Monday in an op-ed in the Washington Post.

Legal experts say such a shift could be implemented only through a constitutional amendment.

“I strongly support 18-year term limits for Supreme Court justices, but I believe that this would require a constitutional amendment, especially if applied to current justices,” said UC Berkeley Law School Dean Erwin Chemerinsky.

Polls show that most Americans support the idea of limiting the terms of Supreme Court justices. It is particularly popular with many Democrats and progressives, who seek to limit the power of the court’s current 6-3 conservative majority.

But amending the Constitution requires the support of two-thirds of the House and Senate and three-quarters of the states.

An Associated Press poll last summer found that 67% of Americans supported the idea of fixed terms for Supreme Court justices rather than the current life terms. This included 82% of Democrats and 57% of Republicans.

The Constitution says judges and justices, once appointed, “hold their offices during good behavior,” which was understood then and ever since to mean they had lifetime terms.

Democrats in the House and Senate have proposed bills that would set an 18-year term for Supreme Court justices and would push the older justices into a semi-retired “senior status” after 18 years on the court. If enacted now, it would push aside three conservatives: Justices Clarence Thomas and Samuel A. Alito Jr. and Chief Justice John G. Roberts Jr.

But the bills have no chance of moving forward in this Congress, and they would face a stiff constitutional challenge if they were enacted in the next Congress.

Georgetown law professor Steve Vladeck wrote that Biden’s “belated push for unattainable (and ineffective) reforms only drives home the opportunities he’s missed to change the national conversation about the Supreme Court…. These reforms have no chance of being adopted, and even if they’re adopted, they’re unlikely to be effective anytime soon.”

When Biden took office in 2021, he was under pressure to do something about the conservative court that had three new Trump appointees. He appointed a presidential commission to study the matter and issue a report, but nothing further was done.

“For most of American history, members of Congress have assumed that the only constitutional way to achieve term limits for Supreme Court Justices is through constitutional amendment,” the report said. “Starting as early as 1807, and continuing to the present, more than two hundred proposals have been introduced in Congress to amend the Constitution to establish term limits for Supreme Court Justices or for federal judges more generally.”

None was adopted. The first bill proposing to set term limits was introduced in 2020, the report noted.

Chemerinsky said setting term limits by law “would be particularly problematic if applied to current justices because they were appointed and confirmed with the clear understanding that they were lifetime appointments.

However, if term limits don’t apply to the current justices, they won’t make a difference for a long time.”

He noted that six of the current justices are under age 70, and conservative Justices Brett M. Kavanaugh, Neil M. Gorsuch and Amy Coney Barrett are likely to serve for 20 years or more.