(Reuters) -A federal judge on Tuesday struck down an executive order targeting law firm WilmerHale, in the third ruling to overwhelmingly reject President Donald Trump's efforts to punish firms he perceives as enemies of his administration.

U.S. District Judge Richard Leon, in Washington, an appointee of Republican President George W. Bush, said Trump's order retaliated against the firm in violation of U.S. constitutional protections for free speech and due process.

"I have concluded that this order must be struck down in its entirety as unconstitutional," Leon wrote in his 73-page opinion. "Indeed, to rule otherwise would be unfaithful to the judgment and vision of the Founding Fathers!"

Leon said Trump had penalized WilmerHale for hiring Robert Mueller, the Republican-appointed special counsel who led a probe into Russia's interference in the 2016 presidential election and Trump campaign ties to Moscow. Trump has derided the investigation as a political "witch hunt."

In a statement, WilmerHale said Leon's ruling "strongly affirms our foundational constitutional rights and those of our clients. We remain proud to defend our firm, our people, and our clients."

White House spokesman Harrison Fields in a statement said Trump acted within his power by rescinding security clearances for the firm's attorneys. Reviewing the president's clearance decisions "falls well outside the judiciary's authority," Fields said.

WilmerHale was among four law firms that sued the administration over Trump's orders, which suspended their lawyers' security clearances and sought to bar them from federal buildings and strip their clients of U.S. federal government contracts.

WilmerHale called Trump's order "flagrantly" unconstitutional, arguing it violated its rights to speech, due process and equal protection under the law. The firm in its lawsuit was represented by prominent conservative lawyer Paul Clement, who was the U.S. solicitor general during the George W. Bush presidency.

Leon barred federal agencies from enforcing the March 27 executive order against WilmerHale, a 1,200-lawyer firm with offices in Washington, D.C., and across the country. He called the order "a staggering punishment for the firm's protected speech" that harmed its ability to represent its clients.

In a related lawsuit, U.S. District Judge Beryl Howell on May 2 overturned Trump's executive order against law firm Perkins Coie. On May 23, U.S. District Judge John Bates issued a similar ruling that struck down Trump's order against Jenner & Block. A fourth judge is weighing whether to overturn an executive order that targeted Susman Godfrey.

The U.S. Justice Department has defended Trump's orders in court, arguing in each case that Trump was lawfully exercising his presidential power and discretion. Trump has accused the firms of "weaponizing" the justice system against him and his allies.

The Justice Department can appeal Leon's order to the U.S. Court of Appeals for the District of Columbia Circuit.

Nine law firms, including Paul Weiss, Latham & Watkins; Skadden Arps; and Willkie Farr, reached deals with Trump that averted punitive actions, pledging a combined total of nearly $1 billion in free legal services to advance causes he supports.

Trump's targeting of firms has drawn condemnation from many within the legal industry. Some have criticized the firms that reached agreements as capitulating to presidential coercion.