Two University of Michigan graduate research assistants have filed a lawsuit against the state over a new law that bars graduate research assistants from unionizing, The Detroit Free Press reported. Republican lawmakers pushed through the legislation just as organizers appeared on the cusp of winning the right to form a union. The suit charges that the law violates the U.S. Constitution's equal protection requirements by creating a special class of workers (graduate research assistants) who are denied rights available to other workers.