The lawsuit, filed Monday evening in federal court in North Carolina, seeks $157 million from the ACC, plus punitive damages, the Washington Post reported.
The ACC kicked off the litigation by asking a court to enforce the conference's $52 million exit fee after school officials announced their move in a bid to get more television revenue out of the Terrapins football program.
Football accounts for an estimated 85 percent of broadcast revenue for most Division I college athletic programs.
The ACC alleged in its suit that Maryland was coached by the Big Ten and ESPN, which has the broadcasting rights for that conference, on how to leave the conference.
In response, Maryland alleges the ACC tried luring away two existing Big Ten schools to offset Maryland's departure. It also charges the ACC has withheld NCAA money.
The university first sought to have the ACC's lawsuit in North Carolina thrown out because "a North Carolina court has no jurisdiction over the sovereign state of Maryland and its public universities."
Courts in Maryland, where litigation is also pending over the matter, have stayed their decisions until the North Carolina lawsuits have been resolved.