U.S. President Donald Trump issued a proclamation on Thursday targeting law firm WilmerHale, one of a handful of major firms the president has taken aim at that have connections to his legal or political adversaries.

The proclamation cited WilmerHale's ties to Robert Mueller, the former U.S. special counsel who investigated Russian contacts with Trump's 2016 presidential campaign.

Like three earlier executive orders issued by Trump against other firms, the proclamation suspended security clearances held by lawyers at WilmerHale, restricted their access to government officials and ordered a review meant to terminate federal contracts held by the firm's clients.

A WilmerHale spokesperson said Trump's proclamation was unlawful and resembled an earlier executive order "that has been enjoined by a federal judge."

Mueller retired from the firm in 2021 after a "long, distinguished career in public service," the spokesperson said. Mueller could not immediately be reached for comment.

The White House did not immediately respond to a request for comment.

AGs warn of 'chilling effect'

A day earlier, the attorneys general in several Democratic states on Wednesday denounced what they called the "chilling effect" of Trump's executive orders targeting law firms and calls for impeaching federal judges, characterizing ongoing attacks as retribution against political opponents.

In what they labelled an "open letter to the legal community," more than 20 attorneys general from states across the country and in Washington, D.C., said the actions "represent a clear threat to our system of justice and our profession."

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Presidential actions targeting law firms have sought "retribution over ideological differences, punishing firms for the actions of individual attorneys representing clients adverse to the President and his supporters," the letter said.

The state attorneys general expressed alarm over law firm Paul Weiss's decision to negotiate an agreement with Trump, a Republican, in exchange for the president rescinding an executive order targeting the firm.

Paul Weiss agreed to terms that included pledging the equivalent of $40 million US in free legal work to support "mutually agreed" administration projects such as combating antisemitism and supporting veterans.

Paul Weiss chairman Brad Karp defended the deal in messages to colleagues, asserting that Trump's executive order risked clients perceiving the law firm as "persona non grata" to the administration and "could easily have destroyed our firm." He said the Trump administration would not dictate the legal work the leading firm would provide under the agreement.

Judge blasts Trump administration 'innuendo'

An executive order against Perkins Coie included a laundry list of Trump grievances, in particular related to the firm's work for the campaign of Democrat Hillary Clinton, his 2016 election rival.

Perkins Coie is challenging in court the order targeting it.

A U.S. judge declined Wednesday to step aside from that very lawsuit after the administration accused her of bias.

U.S. District Judge Beryl Howell said a filing seeking her recusal was "rife with innuendo" and does not "come close to meeting the standard for disqualification."

The department's filing cited Howell's prior remarks in cases against Trump supporters arising from the Jan. 6, 2021, attack on the U.S. Capitol, and her handling of disputes related to federal investigations of him after his first term in office. 

Howell said the Trump administration's criticism "reflects a grave misapprehension of our constitutional order."

Richard Primus, a University of Michigan constitutional law professor who formerly worked at Jenner & Block, said Trump's various orders seek to demonstrate that lawyers will suffer if they oppose the president's interests.

"They are a revenge program, in part," Primus said.

"He doesn't recognize the category of legitimate opposition," he added. "If you are opposed to me, your actions are illegitimate, and you should be shunned, punished and criminalized."

Trump's order aimed at Jenner & Block criticized its legal work supporting the protection of rights for transgender people and immigrants. The order accused the firm of pursuing "partisan goals."

One of the firm's former partners, Andrew Weissmann, served as a lead prosecutor for former special counsel Robert Mueller's team.

Jenner & Block said Tuesday that it "will pursue all appropriate remedies" to challenge Trump's order.

Covington & Burling was hit with a narrower order last month that cited the firm's representation of Jack Smith, the special counsel who brought two federal criminal indictments against Trump, and whose adjudication was essentially ended by the Republican's Nov. 5 election win.

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The state attorneys general also condemned calls from Trump, his billionaire backer Elon Musk and several Republican lawmakers for impeaching federal judges who have ruled against the administration and in some cases blocked executive orders.

Trump lashed out at U.S. District Judge James Boasberg in Washington, who blocked him from using wartime powers to deport Venezuelan migrants.

Task force formed to ensure security of judges

Musk has lambasted judges in more than 30 social media posts since the end of January on his social media site X, calling them "corrupt" or "evil," and deriding what he termed the "tyranny of the judiciary" after judges blocked parts of a federal downsizing measure.

Such calls, and other criticisms, have resulted in federal judges experiencing mounting alarm over their security in response to rising threats directed at them.

The U.S. federal judiciary on Wednesday launched a bipartisan task force focused on ensuring the continued security and independence of the courts, according to a memo reviewed by Reuters.

While some Trump allies have been openly critical of judges, conservative jurists he's nominated to the Supreme Court have also been threatened.

Justice Brett Kavanaugh was the target of an alleged assassination attempt in 2022. Nicholas Roske, the accused, is set for trial in that case in June. 

As well, earlier this month, police were called to the home of the sister of Justice Amy Coney Barrett after a bomb threat targeted the address. Ultimately no bomb was found.