IOWA CITY, Iowa (AP) — A union representing University of Iowa nurses is appealing to the state Supreme Court in an effort to secure a bargaining agreement made before lawmakers limited union bargaining powers. The Iowa City Press-Citizen reports that Service Employees International Union represents 3,500 workers at UI Hospitals and Clinics. It’s appealing a district judge’s ruling that the university’s Board of Regents doesn’t have to honor an employment agreement presented to the union early last year.

The December ruling says the contract wasn’t binding since the board didn’t vote to ratify the agreement. The union ratified the contract days before state legislators limited the bargaining power of public-sector labor unions. Union negotiator Jim Jacobson says lawmakers have rigged the system against workers. A board spokesperson declined to comment on the litigation.