What are the conditions for counterclaiming patent infringement?

(1) The plaintiff is a citizen, legal person and other organization that has a direct interest in the case; (2) Having a clear defendant; (3) Having specific requests, facts and reasons; (4) It falls within the scope of civil litigation accepted by the people's court and is under the jurisdiction of the sued people's court. Other conditions (1) counterclaims can only be brought by the defendant to the plaintiff, not to anyone other than the plaintiff. (2) A counterclaim can only be brought to the court that accepts this complaint. (3) Counterclaim and this lawsuit must apply the same procedure. (4) Counterclaim cannot be the exclusive jurisdiction of other courts. (5) The counterclaim must be related to this claim in fact or law. (6) Time limit for filing. The Supreme People's Court's "Applicable Interpretation" Article 232: "After the case is accepted, the court debate has not yet ended, the plaintiff increases the claim, the defendant makes a counterclaim, and a third party makes a claim related to this case. If the cases can be tried together, the people's court shall try them together. "