FILE PHOTO: A U.S. flag is reflected in the windows of the shuttered former offices of the U.S. Agency for International Development (USAID) in Washington, D.C., U.S., July 22, 2025. REUTERS/Jonathan Ernst/File Photo

By Nate Raymond

(Reuters) -A federal judge has blocked U.S. President Donald Trump's administration from unilaterally cutting billions of dollars of foreign aid authorized by Congress that is set to expire at the end of September.

U.S. District Judge Amir Ali in Washington ruled on Wednesday night that the administration remains under a duty to comply with appropriations laws unless Congress changes them and cannot choose not to spend roughly $4 billion of the $11.5 billion appropriated in 2024, set to expire on September 30.

Some funds from prior appropriations cycles likewise expire on September 30.

Ali said that the Trump administration had "given no justification to displace the bedrock expectation that Congress's appropriations must be followed."

The administration appealed Ali's decision on Thursday, with White House spokesperson Anna Kelly saying in a statement his ruling would not be the final say on the issue.

"President Trump has the executive authority to ensure that all foreign aid is accountable to taxpayers and aligns with the America First priorities people voted for," she said.

Ali's order, if it stands on appeal, would prevent Trump from effectively bypassing Congress to cancel funding appropriated mostly to the U.S. Agency for International Development, which his administration has largely dismantled, as he sought to do last week through a so-called pocket rescission.

A pocket rescission is a maneuver in which a president submits a request to Congress to rescind previously approved funding toward the end of a fiscal year before lawmakers can within a mandatory 45-day window act upon the request, allowing it to go unspent.

Ali, an appointee of Democratic President Joe Biden, previously blocked the administration from withholding the money after concluding that doing so violated separation-of-powers principles embodied in the U.S. Constitution.

A divided panel of the U.S. Court of Appeals for the District of Columbia Circuit recently overturned that decision, holding that a group of nonprofits and businesses suing over the funding could not pursue that type of claim.

But the court left open the ability for the plaintiffs to argue the administration's unilateral decision not to spend funds as Congress directed violated the Administrative Procedure Act, as Ali found.

Ali said he ruled fast to provide higher courts time to weigh in before the funds reach their expiration dates. The administration has already twice before in the litigation asked the 6-3 conservative majority U.S. Supreme Court to intervene.

(Reporting by Nate Raymond in Boston; Editing by Mark Porter and Nia Williams)