A group of Michigan labor unions filed a lawsuit yesterday challenging the constitutionality of Michigan’s recently enacted Right to Work legislation. The lawsuit, filed in the U.S. District Court for the Eastern District of Michigan, challenges only the legislation affecting private employers, claiming that it violates the Supremacy Clause of the federal Constitution because private employers are regulated by federal labor law, not state law. The complaint asks for a declaratory judgment finding the Right to Work legislation invalid.The unions bringing the suit likely have a tough road ahead if they are to succeed in the lawsuit. As we previously covered, a lawsuit challenging Indiana’s Right to Work law under similar theories was soundly dismissed by an Indiana federal court in January, and lawsuits in other states have similarly been unsuccessful. The lawsuit filed Monday is the second to challenge Michigan’s Right to Work law. A previous lawsuit filed in state court claims the law should be invalidated because the way it was passed violates the state’s Open Meetings Act, citing the fact that Michigan’s Capitol Building was closed to the public due to a large number of protestors when the bills were passed on Dec. 6, 2012. The ACLU has stepped in to represent Michigan’s labor unions in that lawsuit, which is pending in Ingham County. The new lawsuit is Mich. State AFL-CIO et al. v. Callaghan et al., Case No. 2:13-cv-10557 (E.D. Mich.). A copy of the complaint is available here. S ee all of our previous Right to Work coverage here.