n.
In law, a plea in response to an allegation that admits its truth but also asserts that it is not sufficient as a cause of action.
In the U.S., demurrers are no longer used in federal procedure (having been replaced by motions to dismiss or motions for more definite statement) but are still used in some states. A general demurrer challenges the sufficiency of the substance of an allegation, whereas a special demurrer challenges the structure or form of an allegation.