Washington — President Biden on Monday unveiled a trio of proposals to reform the Supreme Court, calling on Congress to pass legislation setting term limits for justices and establish binding, enforceable ethics rules for the nation’s highest court.

Mr. Biden’s proposed reforms come after the Supreme Court, which has a 6-3 conservative majority, issued a series of landmark decisions in recent years that have upended longstanding rulings on abortion, affirmative action in higher education and federal regulatory power.

Those decisions, as well as scrutiny over ethics practices at the high court, have made it a target of Democrats and liberal advocacy groups, who have argued the Supreme Court has undermined public confidence in itself.

Two of Mr. Biden’s three proposed changes — term limits and a binding code of conduct — would require action from Congress, making it highly unlikely they will become law before the president leaves office in January 2025. His third reform is a constitutional amendment that clarifies that no president is immune from prosecution for crimes committed while in office. That proposal is Mr. Biden’s answer to the Supreme Court’s ruling earlier this month finding that former President Donald Trump cannot be prosecuted for official acts taken while in the White House.

Here’s what to know about Mr. Biden’s plan for Supreme Court reform.

What are the president’s proposed Supreme Court changes?

The first measure put forth by Mr. Biden is an amendment to the Constitution called the No One is Above the Law Amendment, which would state that the Constitution doesn’t grant immunity from federal criminal indictment, trial, conviction or sentencing to a former president, according to the White House. 

“I share our Founders’ belief that the president’s power is limited, not absolute. We are a nation of laws — not of kings or dictators,” Mr. Biden wrote in an op-ed for the Washington Post about his plan.

The second proposed reform would do away with lifetime appointments for members of the Supreme Court and instead set 18-year term limits. Under Mr. Biden’s plan, the president would appoint a new justice every two years, who would then serve for 18 years. 

“Term limits would help ensure that the court’s membership changes with some regularity,” Mr. Biden wrote. “That would make timing for court nominations more predictable and less arbitrary. It would reduce the chance that any single presidency radically alters the makeup of the court for generations to come.”

The president’s third proposal is a binding code of conduct for the Supreme Court, which would require justices in part to disclose gifts, refrain from public political activity and step aside from cases in which they or their spouses have financial or other conflicts of interest.

The Supreme Court implemented ethics rules in November, but it does not include an enforcement mechanism. Mr. Biden called its ethics code “weak and self-enforced.”

Will these be implemented?

It’s highly unlikely Mr. Biden’s proposed changes will be implemented in the coming months. Election Day is just 99 days away and, more importantly, Congress is divided. The president’s plans to impose term limits and a code of conduct would require legislative approval from the House and Senate.

Republicans narrowly control the House, and GOP lawmakers in both chambers of Congress have denounced Democrats’ criticisms of the court, arguing they are part of an effort to delegitimize the Supreme Court following rulings that they dislike. Legislation setting term limits for justices and establishing ethics rules would be unlikely to clear the House, and that’s if Republican leaders allowed a floor vote in the first place.

Additionally, there is a high bar for amending the Constitution. One method for proposing a constitutional amendment requires two-thirds support of both the House and Senate, and another is through a constitutional convention of two-thirds of state legislatures. Ratification requires support from three-fourths of state legislatures.

The Constitution has been amended 27 times, most recently in 1992.

But progressive groups are working to make the Supreme Court a motivating issue for voters in November. Some initiatives rolled out in recent months are aimed not only at helping Democrats hold onto the White House, but also keep control of the Senate and flip the House.

If Democrats were to gain a trifecta, it could clear the way for Congress to enact legislation reforming the Supreme Court. In the Senate, the party would have to significantly widen its majority, since 60 votes are required for legislation to advance. 

Why is he rolling these out now?

Mr. Biden forecast his reform proposal during remarks in the Oval Office last week, days after announcing his withdrawal from the 2024 presidential race and endorsement of Vice President Kamala Harris. The president said changing the Supreme Court is “critical to our democracy.”

Mr. Biden’s comments — and now his plan — marked a significant shift for the president, who resisted calls to endorse court reforms just a few years ago. During the 2020 election, the president declined to back so-called court packing, or adding seats to the Supreme Court, a proposal pushed by liberal advocacy groups.

Mr. Biden instead created a commission to study proposed changes, and the panel approved and submitted its report to him in December 2021. But the president didn’t publicly address the commission’s findings, even as Congress’ focus on the Supreme Court intensified last year amid concerns about its ethics policies. In his Washington Post op-ed, Mr. Biden thanked the commission for its “insightful analysis, which informed some of these proposals.”

Concerns from Democrats in Congress were sparked by reporting about Justice Clarence Thomas’ ties to GOP megadonor Harlan Crow, who paid for trips that the justice did not report on annual financial disclosure forms.

Thomas said he and Crow have been friends for decades, and the justice didn’t believe he was required to report the travel under prior guidelines for personal hospitality. He vowed last year to comply with new rules and listed additional travel provided by Crow on his latest disclosure forms.

Justice Samuel Alito has also faced backlash from Democrats over an upside-down American flag flown outside his Virginia residence in January 2021 and an “Appeal to Heaven” flag displayed outside his New Jersey vacation house in the summer of 2023.

Both types of flags were carried by rioters who breached the U.S. Capitol building on Jan. 6, 2021. Alito has said he was not involved in the displays outside his homes. Instead, the justice told congressional Democrats in May that his wife flew the two flags, and neither of them knew of the meanings ascribed to them in recent years.

Beyond the ethics practices, Democrats have also taken aim at the Supreme Court because of recent decisions from its conservative majority. In June 2022, the court overturned Roe v. Wade, and in June 2023, it rejected affirmative action in higher education.

In its most recent term, it overturned a 40-year-old decision to curtail the regulatory power of federal agencies, dismantled a Trump-era ban on bump stocks and narrowed the scope of a federal obstruction law used to charge scores of Jan. 6 defendants, including Trump.

The Supreme Court also found that former presidents are entitled to immunity from federal prosecution for official acts taken while in Congress, a ruling with significant ramifications for special counsel Jack Smith’s case against Trump.

Citing the landscape surrounding the court, Mr. Biden wrote that “what is happening now is not normal, and it undermines the public’s confidence in the court’s decisions, including those impacting personal freedoms. We now stand in a breach.”