“College athletes should be able to freely choose the institutions that best meet their academic, personal and professional development needs without anticompetitive restrictions that limit their mobility by sacrificing a year of athletic competition,” DOJ antitrust head Jonathan Kanter said in a statement.

Federal antitrust prosecutors have long had the NCAA on their radar and have filed amicus briefs in private cases in support of college athletes, including a recent U.S. Supreme Court decision that loosened restrictions on their compensation.

The focus of the lawsuit DOJ joined Thursday is a rule delaying athletic eligibility for student athletes transferring schools a second time. Students are immediately eligible after one transfer but must sit out for a year the second time.

The NCAA did not immediately respond to a request for comment. Yet the DOJ’s involvement in the multistate lawsuit emerged the same day federal lawmakers wrangled over a contentious proposal that would grant college sports officials an exemption from federal antitrust law.

According to the lawsuit, the rule “is a no-poach agreement between horizontal competitor member schools that serves to allocate the market for the labor of NCAA Division I college athletes,” referring to agreements typically between employers to not hire each other’s workers.

“It is ironic that this rule, stylized as promoting the welfare of college athletes, strips them of the agency and opportunity to optimize their own welfare as they see fit,” the states and DOJ argued in the lawsuit.