BURLINGTON — The Vermont Supreme Court has ruled that the director of the University of Vermont’s student health center was not legally liable for the actions of a physician assistant who improperly prescribed opiate medications to 12 students.

The court’s decision affirms a ruling by the state Medical Practice Board that cleared Dr. Jon Porter in his oversight of a longtime physician assistant.

Porter was accused of failing to supervise Peter Nobes, who refilled opiate prescriptions supposedly lost or stolen, and prescribed opiate medications to students without evidence that a physical exam or a visit had occurred.

The board rejected a recommendation that Porter be found guilty of unprofessional conduct but not face any disciplinary action.

The attorney general’s office appealed the decision.