This case, which involved four related lawsuits between the shareholders of a closely held corporation, contains a discussion of when a claim is a compulsory counterclaim. The Court said "Rule 13(a) of the North Carolina Rules of Civil Procedure provides that a party is required to plead as a counterclaim: (1) “any claim which at the time of serving the [responsive] pleading the pleader has against any opposing party”; (2) “if it arises out of the transaction or occurrence that is the subject matter of the opposing party’s claim”; and (3) if it “does not require for its adjudication the presence of third parties of whom the court cannot acquire jurisdiction.” N.C. R. Civ. P. 13(a) (2007)."
The Court dismissed some of the claims, finding that they should have been brought in an earlier action, and discussed also the distaste of North Carolina courts for claim splitting. It held "North Carolina law requires that all damages incurred as a result of a single injury, transaction, or occurrence be recovered in one lawsuit."
The Court also held that an individual shareholder was not entitled to maintain a derivative action on a pro se basis, ruling that "an individual non-attorney litigant may not proceed derivatively on behalf of a corporation without counsel." This would presumably have been the unauthorized practice of law. The Court said there was no authority in North Carolina on this point.