Definition[]
A compulsory counterclaim (also called a mandatory counterclaim) is a counterclaim that must be brought in a pending legal action or it will be waived.
U.S. federal courts[]
Under the U.S. Federal Rules of Civil Procedure, a counterclaim is compulsory if it involves only the parties currently part of the suit, and "arises out of the transaction or occurrence that is the subject matter of the opposing party's claim."[1]
References[]
- ↑ Federal Rules of Civil Procedure, Rule 13(a)(1)(A) (full-text).