A senior federal judge in Washington, D.C., on Friday halted Justice Department subpoenas directed at the Federal Reserve Board of Governors, ruling that prosecutors failed to present credible evidence supporting a criminal investigation into Jerome Powell.

In an unsealed opinion, U.S. District Judge James Boasberg concluded that the government had offered “essentially zero evidence” to justify the subpoenas. He wrote that the available record strongly suggested the effort was intended to pressure Powell rather than to pursue legitimate criminal concerns.

“There is abundant evidence that the subpoenas’ dominant, if not sole, purpose is to harass and pressure Powell either to comply with the president’s wishes or to step down so another Federal Reserve chair can be installed,” Boasberg wrote.

The judge added that the Justice Department’s reasoning for investigating Powell was “thin and unsubstantiated,” concluding that the claims appeared pretextual.

The ruling drew immediate criticism from acting U.S. Attorney Jeanine Pirro, who labeled Boasberg an “activist” judge and said the government plans to appeal the decision.

“This is the antithesis of American justice,” Pirro said during a news conference, arguing that dismissing the case without a full investigation or questioning undermines the legal process.

The Justice Department inquiry had focused on Powell’s testimony to Congress last year regarding cost overruns tied to a multibillion-dollar renovation project at the Federal Reserve’s headquarters.

A spokesperson for the Federal Reserve System declined to comment on the ruling.

Powell previously criticized the investigation in a January video message, calling it a politically motivated attempt to influence the Federal Reserve’s decisions on interest rates.