Counter claim is a civil litigation system relative to the main claim (or original claim), which refers to the independent counterclaim made by the defendant of the main claim to the people's court with the plaintiff of the main claim as the defendant in the already started litigation process. The purpose of counterclaim is to merge with the main claim for trial, in order to achieve the purpose of offsetting and annexing all or part of the plaintiff's claims. To file a counterclaim, the following conditions must be met:
1. The counterclaim must be based on the main claim. Counter claim and main claim are two inseparable systems. Without main claim, there can be no counter claim. Therefore, a counterclaim can only be filed by the defendant of the main lawsuit, that is, the defendant of the counterclaim must be the plaintiff of the original lawsuit, the plaintiff of the counterclaim must be the defendant of the original lawsuit, and other participants in the lawsuit and outsiders have no right to file a counterclaim. 2. The counterclaim must be filed after the filing of the main lawsuit, before the people's court declares the judgment, or before the mediation agreement is served. 3. The counterclaim and the main claim must be under the jurisdiction of the same people's court. 4. A counterclaim and the main claim must have a substantial connection, that is, the counterclaim and the main claim or reason for litigation must be based on the same facts or legal relationship in order to file a counterclaim.
