Alfred Procopio Jr.’s decadeslong fight with the U.S. Department of Veterans Affairs changed the law, forcing the agency to provide potentially billions of dollars in benefits for thousands of Vietnam War veterans. But his dispute with the government hasn’t ended, as his lawyer presses an appeal in the U.S. Supreme Court to collect $35,000 in legal fees.

The petition tests a key element of the Equal Access to Justice Act, or EAJA, a federal law that allows private parties who prevail against federal agencies in certain circumstances to recoup the cost of litigation. An award of fees under the EAJA is mandatory when a court concludes that the government’s position was not “substantially justified.”