More than 100 former senior Department of Justice officials have signed an amicus brief calling on a Virginia federal judge to throw out criminal charges against an embattled former FBI director, James Comey, which they described as “a dangerous exercise of prosecutorial power.”

A significant majority of the brief’s signatories are from Democratic administrations, with a few Republicans included — and at least one official who joined during the first Trump administration. The signatories include notable Trump adversaries like Lanny Breuer, who is representing Jack Smith; Hampton Dellinger, who sued President Trump unsuccessfully to keep his government job; Attorney General Eric Holder; a top deputy to Robert Mueller, Jeannie Rhee, and a vocally anti-Trump conservative former judge, Michael Luttig.

The amicus brief, filed Monday, warned U.S. District Judge Michael S. Nachmanoff, a Biden appointee, that the Trump justice department’s “vindictively motivated” indictment — which charges Mr. Comey with making a false statement and obstruction — could carry greater implications for “the rule of law and free society in this Nation more broadly” if allowed to proceed.

“It would send a dangerous signal, short-circuiting whatever internal guardrails remain within the Department, and emboldening the government to target others in exactly the way that then-Attorney General (Robert H.) Jackson feared: for ‘being personally obnoxious to or in the way of’ the Executive Branch,” the filing reads.

In September, Mr. Comey was charged with making a false statement and obstruction in Senate Judiciary Committee testimony in which he denied authorizing an FBI employee to “be an anonymous source in news reports” about the FBI’s investigations into both Mr. Trump and Secretary Hillary Clinton. He has pleaded not guilty.

Last week, attorneys for Mr. Comey filed two motions calling on Judge Nachmanoff to dismiss the government’s prosecution against him, accusing Mr. Trump of directing a retaliatory case and calling the interim U.S. attorney for Eastern Virginia, Lindsey Halligan, who is overseeing the matter, “invalidly appointed.” 

Ms. Halligan advanced criminal charges against Mr. Comey and New York’s attorney general, Letitia James, after her predecessor, Erik Siebert, was forced out following Mr. Trump’s objection to the strong support he received from Virginia’s two Democratic senators. According to ABC News, Mr. Siebert was also resisting pressing charges against Ms. James and Mr. Comey.

Earlier this month, Ms. Halligan, a former personal attorney for Mr. Trump on the Mar-a-Lago documents case who most recently had been assigned to address allegations of bias and race-baiting at the Smithsonian, fired two lawyers in her office, reportedly over their resistance to pursuing charges against Ms. James, who was ultimately charged with bank fraud and making false statements to a financial institution. 

In the amicus filing, the group characterized Ms. Halligan as a “stalking horse” for Mr. Trump’s “evident retributive animus.”

The filing also argued relief was merited in Mr. Comey’s case and will prevent any “similar future abuses of prosecutorial power.”

The group said it hoped the collective experience and credibility of those behind the brief will compel Judge Hirschorn to see the case as a politically motivated prosecution.

A former Eastern District of Virginia prosecutor, Samantha Bateman, who left the DOJ in March, told the Washington Post that the goal of the amici was to “speak out and show how important this matter is and show some background knowledge on the department processes and norms.”

She added: “It appears that those venerable practices, policies and norms were not followed.”