CHICAGO (AP) — Nine state workers who are no longer members of the American Federation of State, County and Municipal Employees are seeking the return of some the fees paid the union.

In the lawsuit filed Wednesday, the Liberty Justice Center contends more than 2,700 state employees are entitled to money they paid to AFSCME from May 1, 2017 through June 28, 2018. The U.S. Supreme Court last year ruled it unconstitutional to make public employees pay union dues.

Mark Janus, who was behind the lawsuit that resulted in the Supreme Court ruling, was the plaintiff in a similar lawsuit that was thrown out earlier this year by U.S. District Judge Robert Gettleman. The judge ruled AFSCME followed the law in collecting fair share fees.

AFSCME spokesman Anders Lindall says corporate-funded front groups are using the courts to “further their political attack on working people and our union.”