The ACC sued Maryland when university officials announced in November that the school was leaving for the Big Ten after being a charter member of the ACC.
David Paulson, Gansler's spokesman, said Monday night that "the state is going to be be considering its options in light of this ruling."
The attorneys for the university have 30 days to appeal Monday's ruling.
An attorney for the university argued that since the school is state-funded, it is protected from lawsuits by sovereign immunity.
The ACC's attorney argued that sovereign immunity is not part of contractual claim in North Carolina.
The ACC is headquartered in Greensboro, N.C.
Both ACC attorney Alan Duncan and Maryland attorney Alex Barrett declined comment, according to WRAL-TV in Raleigh, N.C.
A spokesman for Maryland president Wallace Loh referred all calls to the Attorney General's office.
After his office filed a complaint last month on behalf of the University System of Maryland, the Board of Regents and the university, Maryland Attorney General Douglas Ganler called the exit fee "an antitrust violation and an illegal penalty", adding that "our motion in North Carolina will ensure that a Maryland court will rule on the case."