To overthrow; to annul; to make void or declare invalid; e.g., quash a subpoena.. Unreasonable, obviously irregular, or oppressive subpoenas, injunctions, indictments, and orders can be quashed by a court.For example, if jurors have been selected improperly, the court can quash the proceedings.hen the application to quash is made on the part of the defendant, the court generally refuses to quash the indictment when it appears some enormous crime has been committed. Com. Dig. Indictment, H; Wils. 325; 1 Salk.