Republican lawmakers are criticizing courts that reimburse environmental litigants for their legal costs, and the Trump administration is asking them to change the law to make it harder to recover these costs.

Justice Department attorneys are often hamstrung in environmental cases by laws that allow plaintiffs to recover their legal fees from the federal government, Jonathan Brightbill, the deputy assistant attorney general in charge of defending environmental agencies, told a congressional hearing.

Brightbill said lawmakers need to change these...