in law, a process whereby a party hypothetically admits as true certain facts alleged by the opposition but asserts that they are not sufficient grounds for relief, or redress. A ruling on a demurrer can result in the quick disposition of a case resting on the point of law challenged in the demurrer.

In criminal law a demurrer is usually based upon some defect in an indictment or the claim that the facts presented do not constitute a felony (felony and misdemeanour) or other serious crime. In civil cases demurrers also are based often upon some error or omission. A general demurrer attacks the general substance of an indictment or plea; a special demurrer attacks its structure or form or one specific part of it.