On the eve of a new year and a second Trump presidency, Chief Justice John Roberts issued a stark warning to the incoming administration, members of Congress and the public about threats to the nation’s independent judicial system and the rule of law.

“Within the past few years, elected officials from across the political spectrum have raised the specter of open disregard for federal court rulings. These dangerous suggestions, however sporadic, must be soundly rejected,” Roberts wrote in his annual year-end report on the federal judiciary.

“Every Administration suffers defeats in the court system — sometimes in cases with major ramifications for executive or legislative power or other consequential topics,” Roberts said. “Nevertheless, for the past several decades, the decisions of the courts, popular or not, have been followed, and the Nation has avoided the standoffs that plagued the 1950s and 1960s.”

Roberts’ decision to address partisan criticism of the judiciary directly is notable for a figure who has studiously avoided public commentary on politics or matters of public debate.

The message publicly highlights what has been a growing private concern among the justices: that an intensifying storm of partisan rhetoric, attacks on the court’s credibility by outside groups and public dissatisfaction with some recent high-profile decisions may empower open defiance of the Supreme Court’s authority.

There has also been deep unease about persistent protests outside justices’ homes and threats of violence, which have resulted in around-the-clock security measures.

President-elect Donald Trump has harshly attacked the court for unfavorable decisions over the past eight years, with some allies suggesting certain rulings could be ignored.

More recently, Trump has come to the Supreme Court’s defense, suggesting that critics of the justices should be jailed.

“They were very brave, the Supreme Court, very brave, and they take a lot of hits because of it — it should be illegal what happens,” Trump said during a campaign rally in September.

Roberts, the President George W. Bush appointee who is in his 20th year as chief justice, said he welcomes criticism of the court from all corners of society and that criticism alone is not a threat to judicial independence.

However, he said “illegitimate activity,” including violence, intimidation tactics, disinformation and open threats of defiance, risks undermining the democratic system.

Roberts noted more than 1,000 “serious threats” against federal judges investigated by the U.S. Marshals Service in the last five years, resulting in more than 50 people criminally charged.

He warned of a rising tide of “doxing” federal judges and grassroots campaigns to bombard their offices with threatening messages. He also cited foreign misinformation efforts on social media to distort the meaning of judicial rulings.

“Public officials certainly have a right to criticize the work of the judiciary, but they should be mindful that intemperance in their statements when it comes to judges may prompt dangerous reactions by others,” Roberts wrote.