Counter suing

In a court of law, a party's claim is a counter-claim if the defending party has previously (in the present action) made a claim against the claiming party.

Examples of counterclaims include:

In U.S. federal courts, counterclaims can arise on various occasions, including e.g.:

Dependent upon the location of where the lawsuit was originated, the defending party has a period of time to file a countersuit, also known as a counter claim, against the claiming party. This is a direct claim from the defending party against the party who initiated the lawsuit for concurrent claims, including being wrongfully sued.

A crossclaim is a pleading made against a party who is a co-defendant or co-plaintiff. A cross claim is against anyone who is "on the same side of the lawsuit". An example of this is a manufacturing company who ships their product through a 3rd party transportation company to the buyer. Upon the products being inspected by the buyer, the buyer finds that the product has been damaged in shipping and refuses to pay. If the manufacturer sued the buyer, the buyer would serve an answer with a denial that the buyer owed money to the manufacturer and a crossclaim to the shipping company to compensate for the damages.

Under the FRCP, counterclaims are either compulsory or permissive.

Permissive counterclaims comprise "any claim that is not compulsory." Such claims may be brought, but no rights are waived if they are not. Courts rarely give permissive counterclaims the necessary supplemental jurisdiction to be brought.

A claim is a compulsory counterclaim if, at the time of serving the pleading,

This last (fourth) requirement is explained in the official notes as follows:

When a defendant, if he desires to defend his interest in property, is obliged to come in and litigate in a court to whose jurisdiction he could not ordinarily be subjected, fairness suggests that he should not be required to assert counterclaims, but should rather be permitted to do so at his election. If, however, he does elect to assert a counterclaim, it seems fair to require him to assert any other which is compulsory within the meaning of Rule 13(a). Clause (2), added by amendment to Rule 13(a), carries out this idea. It will apply to various cases described in Rule 4(e), as amended, where service is effected through attachment or other process by which the court does not acquire jurisdiction to render a personal judgment against the defendant. Clause (2) will also apply to State courts jurisdictionally grounded on attachment or the like, and removed to the Federal courts.

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Wikipedia