A motion to strike is a request by one party in a United States trial requesting that the presiding judge order the removal of all or part of the opposing party's pleading to the court. These motions are most commonly sought by the defendant, as to a matter contained in the plaintiff's complaint; however, they may also be asserted by plaintiffs to a defendant's answer or other pleadings such as cross-complaints. The Federal Rules of Civil Procedure states that "The court may strike from a pleading an insufficient defense or any redundant, immaterial, impertinent, or scandalous matter."
A motion to expunge is a petition by one party in a United States trial requesting that the presiding judge order the erasure of all or part of the opposing party's submission to the court. These motions are most commonly sought by the defendant, as to a matter contained in the plaintiff's complaint; however, they may also be asserted by plaintiffs to a defendant's answer or other submissions such as counterclaims.