A common defense manuever in civil litigation is to file a counterclaim against the plaintiff. Practically, it may put the plaintiff on the back foot with now having to defend a suit and strategically exposes them to potential unanticipated risk/liabilities. Legally, it is sometimes necessary for a defendant to file the counterclaim under the compulsory counterclaim rule.
It is necessary for a defendant to file a counterclaim when the defendant has a claim that “arises out of the transaction or occurence” that is the subject matter of the plaintiff’s claim and does not require additional parties of whom the court cannot acquire jurisdiction. Rule 55.32 lists further circumstances in which a compulsory counterclaim need not be made by a defendant.
The purpose of the compulsory counterclaim rule is to be efficient. It is intended to serve as a means of bringing all logically related claims into a single litigation, through the penalty of precluding the later assertion of ommited claims. State ex rel. J.E. Dunn, Jr. & Associates, Inc. v. Schoenlaub, 668 S.W.2d 72, 75 (Mo. 1984). Therefore, if a defendant fails to file the compulsory counterclaim, it cannot sue on the claim at a later date.