T-Minus 4

Counterclaims - In a case in federal court, a defendant must assert those mandatory counterclaims which arise out of the same transaction or occurrence as the plaintiff's claim. If it does not assert them, it will be deemed to have waived them forever. A defendant may also assert any other claim it has against the plaintiff as a permissive counterclaim, which need not arise out of the same transaction or occurrence. The defendant is also free to pursue permissive counterclaims in a separate forum. In all cases, the federal court must have subject matter jurisdiction over the claims, meaning federal question or diversity. If there is no such jurisdiction, the court may exercise supplemental jurisdiction if the claim arises out of the same transaction or occurrence.