Rule 13 - Counterclaim and Cross-claim.(a) Compulsory Counterclaims. Except in residential landlord/tenant actions, a pleading shall state as a counterclaim, limited to the jurisdiction of the District Court, any claim which at the time of serving the pleading the pleader has against any opposing party, if it arises out of the transaction or occurrence that is the subject matter of the opposing party's claim and does not require for its adjudication the presence of third parties of whom the court cannot acquire jurisdiction, except that such a claim need not be so stated if at the time the action was commenced the claim was the subject of another pending action, or if the opposing party's claim is for damage arising out of the ownership, maintenance, operation, use, or control of a motor vehicle by the pleader. If the counterclaim exceeds the jurisdiction of the District Court, it is not considered a compulsory counterclaim.(b) Permissive Counterclaims. A pleading may state as a counterclaim, limited to the jurisdiction of the District Court, any claim against an opposing party.(c) Counterclaim Exceeding Opposing Claim. A counterclaim may or may not diminish or defeat the recovery sought by the opposing party. It may claim relief exceeding in amount or different in kind from that sought in the pleading of the opposing party.(e) Counterclaim Maturing or Acquired After Pleading. A claim which either matured or was acquired by the pleader after serving his pleading may, with the permission of the court, be presented as a counterclaim by supplemental pleading.(f) Omitted Counterclaim. When a pleader fails to set up a counterclaim through oversight, inadvertence, or excusable neglect, or when justice requires, he may by leave of court set up the counterclaim by amendment.(g) Cross-claim Against Co-party. A pleading may state as a cross-claim any claim by one party against a co-party arising out of the transaction or occurrence that is the subject matter either of the original action or of a counterclaim therein or relating to any property that is the subject matter of the original action. Such cross-claim may include a claim that the party against whom it is asserted is or may be liable to the cross-claimant for all or part of a claim asserted in the action against the cross-claimant.(h) Additional Parties May Be Brought in. When the presence of parties other than those to the original action is required for the granting of complete relief in the determination of a counterclaim or crossclaim, the court shall order them to be brought in as defendants as provided in these rules.(i) Separate Trials; Separate Judgments. If the court orders separate trials as provided in Rule 42(b), judgment on a counterclaim or crossclaim may be rendered in accordance with the terms of Rule 54(b) even if the claims of the opposing party have been dismissed or otherwise disposed of.(j) Electronic Filing of Counterclaims and Cross-claims. When using the EFS, all counterclaims and cross-claims shall be filed in accordance with Rule 1(b)(3).