A federal judge has blocked an attempt by the Trump administration to subpoena Minnesota Gov. Tim Walz and other state officials, accusing the Justice Department of using its investigatory powers to retaliate against state officials for not cooperating with federal efforts to crack down on illegal immigration.

In a ruling unsealed Monday, U.S. District Judge Patrick Schiltz found the “dominant purpose” of the subpoenas was to “coerce Minnesota officials into assisting the federal government with enforcing civil immigration law and to harass and retaliate against them for failing to do so.”

Tensions between the Trump administration and Minnesota’s Democratic leaders escalated in January as federal immigration officers clashed with protesters in the Minneapolis-St. Paul area, especially after officers’ fatal shootings of Renee Good and Alex Pretti.

President Donald Trump even threatened to invoke the Insurrection Act to quell protests and accused Walz, who was Democratic presidential nominee Kamala Harris’ running mate in 2024, and others of encouraging protesters to disrupt Immigration and Customs Enforcement activity.

The subpoenas seeking records were served in January as part of an investigation into whether Walz and other officials obstructed or impeded law enforcement actions. They were sent to the offices of Walz, Attorney General Keith Ellison, Minneapolis Mayor Jacob Frey, St. Paul Mayor Kaohly Her and officials in Ramsey and Hennepin counties.

The ruling is the latest rebuke by the federal judiciary of Justice Department efforts to aggressively implement the Trump administration agenda in courts and target the president’s political adversaries through subpoenas and similar demands.

The judge ruled that there appeared to be “extremely weak to nonexistent” connections between the information sought in the subpoenas and any possible criminal violation. The subpoenas seek materials “that largely if not entirely relate to constitutionally protected conduct,” the judge wrote, noting that Minnesota has the legal right not to devote its resources to enforcing federal immigration law.

The Justice Department “is not conducting a criminal investigation,” the judge wrote, “but is instead using the grand jury process for other (unlawful) purposes.”

The evidence that the subpoenas were issued for unlawful reasons is overwhelming, the judge said, arguing that the Justice Department “has struggled — without success — to identify a single plausible investigatory justification” for them.

The Justice Department said in a statement that it “takes the unlawful obstruction of federal law enforcement operations extremely seriously and will continue to act in full compliance with the law to investigate these matters.”

Over the last year, judges have dismissed indictments against two prominent Trump foes, former FBI Director James Comey and New York Attorney General Letitia James, and grand juries have repeatedly refused to return indictments sought by the Justice Department.

The moves reflect mounting public concerns that the Justice Department, an institution meant to make investigative and prosecution decisions independent of the White House, is being politicized under the current Trump administration.

Vice President JD Vance has separately called on the Justice Department to investigate Walz and Ellison over allegations they failed to stop widespread social services fraud, though the department has not said whether it will open an investigation. Walz and Ellison have described those allegations as politically motivated and defended their efforts to combat fraud in Minnesota.

Meanwhile, other legal battles related to the immigration surge continue. The federal government has suggested Minnesota prosecutors don’t have jurisdiction to investigate federal officers.

Hennepin County Attorney Mary Moriarty in March sued the administration for access to evidence in the Good and Pretti killings, accusing the administration of withholding evidence from state investigators. Moriarty also has pursued criminal charges against ICE officers in two other incidents, including the nonfatal shooting of a Venezuelan man, and suggests her office is investigating several other cases as well.