▶ Watch Video: Supreme Court hears arguments in antitrust case against the NCAA Washington — Supreme Court Justice Stephen Breyer on Tuesday cautioned against adding seats to the nation’s highest court, as some liberal activists are urging to weaken the power of its conservative majority, with Breyer warning that doing so could erode the public’s trust in the institution. In remarks delivered remotely to Harvard Law School, Breyer, one of the Supreme Court’s three liberal justices, said his speech “seeks to make those whose initial instincts may favor important structural or other similar institutional changes, such as forms of court-packing, think long and hard before embodying those changes in law,” according to The Associated Press and Washington Post, citing his prepared remarks. Breyer said the Supreme Court’s authority rests on “a trust that the court is guided by legal principle, not politics” and warned that “structural alteration motivated by the perception of political influence can only feed that perception, further eroding that trust.” Progressive groups and some Democrats have been advocating for expanding the Supreme Court as a way of diluting its 6-3 conservative majority. Calls for more seats to be added to the high court amplified during former President Donald Trump’s tenure, as he named three justices to the bench, shifting it ideologically to the right. President Biden said in October he is “not a fan” of growing the Supreme Court beyond its nine members and vowed to create a commission to issue recommendations on how to reform the court system. Details of the commission, however, have been scant. While the Supreme Court boasts a conservative majority, Breyer pushed back on the characterization of it as a “conservative” court, pointing to the justices’ refusal to wade into legal disputes over the results of the 2020 presidential election. Mr. Trump has lambasted the Supreme Court for refusing to deliver him a second term in office, claiming the justices were “gutless, and will go down in history as such.” “The court’s decision in the 2000 presidential election case, Bush v. Gore, is often referred to as an example of its favoritism of conservative causes,” he said, according to the reports. “But the court did not hear or decide cases that affected the political disagreements out of the 2020 Trump v. Biden election.” He also cited the 2012 ruling upholding the Affordable Care Act, the health care law championed by Democrats, as well as other recent decisions involving politically fraught issues. “It did re-affirm precedents that favored a woman’s right to an abortion,” Breyer said. “It did find unlawful certain immigration, census, and other orders, rules, or regulations, favored by a conservative president.” But Breyer also acknowledged the Supreme Court issued other rulings “that can reasonably be understood as favoring ‘conservative’ policies and disfavoring ‘liberal’ policies. These considerations convince me that it is wrong to think of the court as another political institution.” At 82 years old, Breyer is the oldest and most senior member of the Supreme Court’s shrunken liberal wing. Nominated by former President Bill Clinton in 1994, he is facing growing pressure to resign his seat on the high court to allow Mr. Biden to name a successor. The president has promised to nominate the first Black woman to the Supreme Court should a vacancy arise, and Democrats currently have a razor-thin majority in the Senate, with Vice President Kamala Harris casting tie-breaking votes.