The American Bar Association and a group of individual public interest lawyers sued the U.S. Department of Education on Tuesday claiming that the agency illegally walked back a loan-forgiveness program meant to encourage attorneys to take low-paying public-sector positions.

The lawsuit, filed Tuesday in federal court in Washington, claims that the department has arbitrarily tightened its definition of what sorts of organizations qualify as providers of “public interest law services” under the Public Service Loan Forgiveness Program. The moves, the lawsuit contends, have illegally trimmed the ranks of lawyers who qualify for the program enacted in 2007 by President George W. Bush, which forgives student loan debt for full-time public interest lawyers. To be eligible, attorneys must work in the public sector for 10 years and pay down their loans.