A federal judge in Rhode Island has blocked the EPA’s attempt to terminate the Biden-era “Solar for All” program, a $7 billion grant initiative designed to expand residential solar access in underserved communities. U.S. District Judge Mary McElroy ruled that the agency acted unlawfully in canceling grants that had already been obligated, concluding that Congress had clearly authorized the funding and intended the program to move forward.

The lawsuit, Rhode Island AFL-CIO et al v. Environmental Protection Agency et al, is notable not only because of the amount at stake, but also because it highlights a recurring separation-of-powers dispute: how far an executive agency can go in unwinding programs that Congress has funded and the government has already put into motion.

Judge McElroy’s decision appears to turn on a straightforward but powerful administrative-law principle.