The Center for Individual Rights, an advocacy group that opposes affirmative-action preferences, filed a lawsuit in Michigan state court on Tuesday seeking to compel the University of Michigan at Ann Arbor to immediately bring its policies into line with a ban on such preferences that took effect last month.

The lawsuit accuses the university of dragging its feet in complying with Proposal 2, an amendment to the state Constitution that prohibits public colleges and other state agencies from operating affirmative-action programs that grant preferences based on race, color, ethnicity, national origin, or gender. The lawsuit, which seeks class-action status, was filed on behalf of a white student who had applied to Michigan’s law school and any other student in a similar situation.

The lawsuit disputes the university’s assertion that the meaning of the constitutional amendment is unclear, and argues that the university already has had plenty of time to adjust its policies. In a decision issued last week, the U.S. Court of Appeals for the Sixth Circuit invalidated a December 19 ruling by a U.S. district court giving the university’s three campuses, Michigan State University, and Wayne State University until the end of their current admissions cycles to comply with the amendment.

The University of Michigan responded to the Sixth Circuit’s ruling by telling its administrators and faculty members to put admissions on hold until January 10, so officials there could sort out what the amendment requires. Under the state’s Constitution, the amendment was supposed to take effect on December 23.