Donald Trump’s second administration has shown an “unprecedented degree of resistance” to adverse court rulings, experts say, part of a forceful attack on the American judiciary that threatens to undermine the rule of law, undercut a co-equal branch of government and weaken American democracy.

The attacks, experts say, threaten one of the fundamental pillars of American government: that the judicial branch has the power to interpret the law and the other branches will abide by its rulings.

The attack came to a head this week when the Trump administration ignored an order from US district judge James Boasberg to turn planes carrying deportees around. “I don’t care what the judges think,” Thomas Homan, charged with enforcing Trump’s deportation agenda, said in a Fox News television interview on Monday as the decision came under scrutiny. The next day, Trump called for Boasberg to be impeached, calling him a “radical left lunatic”.

For months, the Trump administration has made it clear they believe they can ignore judicial orders. “Judges aren’t allowed to control the executive’s legitimate power,” vice-president JD Vance tweeted on 9 February. Elon Musk, Trump’s top adviser, has repeatedly called for impeaching judges, and is donating to Republicans in Congress who have supported doing so. House Republicans have introduced resolutions to impeach Boasberg and four other judges who have ruled against Trump.

Trump’s call for impeachment prompted a rare public rebuke from chief justice John Roberts, who said in a statement on Wednesday: “For more than two centuries, it has been established that impeachment is not an appropriate response to disagreement concerning a judicial decision. The normal appellate process exists for that purpose.”

Stephen Vladeck, a law professor at Georgetown University who studies the federal courts, said there was no parallel situation in American history. Trump officials, he said, were trying to see what they could get away with in front of federal judges.

“They’re testing the fences in ways in which they can claim plausible deniability when congressional Republicans say, you can’t defy the courts,” he said. “Whether you call it a crisis or not, this is certainly an unprecedented degree of resistance on the part of the executive branch to adverse court rulings.”

J Michael Luttig, a well-respected former conservative federal judge, said on MSNBC on Tuesday that “America is in a constitutional crisis”. “The president of the United States has essentially declared war on the rule of law in America,” he said.

Luttig told the Guardian that he believed the US supreme court’s ruling last summer finding Trump had immunity from criminal prosecution for official acts undergirded his attacks on the courts. “It is the reason for his emboldenment,” he said.

During Trump’s first administration, the federal courts played a major role in constraining administration policies that violated the US constitution and federal law. Of the 246 cases litigated involving efforts to implement policies through federal agencies, the Trump administration won 54 cases and lost 192 cases or withdrew the actions, according to the Institute for Policy Integrity at New York University.

Since Trump’s second term began in January, more than a dozen judges have blocked his executive actions, including efforts to mass fire federal workers, freeze federal funding and end birthright citizenship.

During the first Trump administration, Vladeck noted, officials appeared more willing to “go back to the drawing board” to rework policies after they had been halted by the courts to make them comply with the law, he said.

“You saw a lot more effort to rationalize everything the administration was doing in law, as opposed to in power,” he said.

The attack on the judiciary has not just included impeachment, but also has extended to personal attacks on judges, prompting concerns about their safety. Supreme court justice Amy Coney Barrett’s sister received a hoax bomb threat, the New York Times reported. Some of the attacks have included sending pizza orders to the homes of judges and family members as a way of threatening jurists that the public knows where they live.

Another judge, John Coughenour of the western district court in Washington, told the Times he had been the victim of a “swatting” attempt in which law enforcement descended on his home after he blocked a Trump administration order ending birthright citizenship.

Unlike politicians and public figures, judges are prohibited from speaking out on political matters and saying anything about a case that could give the impression they are biased. That leaves them unable to correct misinformation and respond to attacks against them.

“It is difficult when you’re in a position where you can’t necessarily traditionally respond to what you think might be unfair and unwarranted attacks,” said Esther Salas, a federal district judge in New Jersey who has been outspoken about the need for protections for jurists after an unhappy litigant killed her son in 2020 and shot her husband at their home.

“I will tell you that judges are human, just like everybody else. We have emotions, we have fears, we have concerns for our family members and for our own safety,” she said. “It does impact a judicial officer.”

Judges have some tools at their disposal to force compliance with their orders. They can sanction attorneys, or if a party refuses to comply with a directive, a judge can issue civil or contempt orders. A civil contempt order, which could be something like a daily fine, punishes the non-compliant party until they adhere to a court ruling. Criminal contempt is more akin to a prosecution. In 2017, Trump pardoned Joe Arpaio after the former sheriff was found in criminal contempt of court.

Federal courts also depend on US marshals, who are part of the justice department to enforce their rulings, prompting concerns Trump could interfere with their functioning.

Indeed, Boasberg has already asked the Trump administration to “show cause” as to why the administration did not comply with his ruling to turn around the plane.

But a motion of contempt and a finding of one often comes at the end of a long legal process and there can be long legal disputes about whether a party is actually complying with a court order.

When a court blocked the Trump administration’s freeze of federal funds, for example, there was evidence the administration was not complying. The 22 states that sued filed a motion to enforce the court’s ruling, which they won, and were considering asking for a contempt order, but ultimately decided not to, Letitia James, the New York attorney general, one of the state attorneys general involved in the suit, said on Thursday.

“We were considering a motion for contempt, but there was some explanations that they provided to us,” she said. They went ahead with the motion to enforce, which released the remaining funds, she told reporters at an event on Thursday.

Vladeck speculated there were other actions courts could take if the Trump administration’s defiance reached a “break the glass moment”. The government, he said, relies on the federal courts for many things, including approving warrants and allowing criminal cases to proceed.

“If noncompliance in case A led courts to be less likely to do the federal government’s bidding in case B, that’d be a real problem from the government’s perspective,” he said. The federal court in Washington , for example, could hypothetically dismiss all of the indictments the government brought out of hand. “That would be quite an escalation, but I think we’d be in response to quite a provocation.”

But the larger point, Vladeck said, was that no one benefits from an unstable legal system in the United States. Economic markets depend on everyone being able to accept that the judgments of courts will be followed.

“There’s no long-term political endgame that results from openly defying a judgment,” he said.

Rachel Leingang contributed reporting