कानून में मुकदमा एक नागरिक-क्रिया है जो किसी न्यायालय के समक्ष की जाती है। इसमें अभ्यर्थी (plaintiff) न्यायालय से विधिक उपचार या साम्या की याचना करता है। अभ्यर्थी की शिकायत पर एक या अधिक प्रतिवादी (defendant) अपनी सफाई देते हैं। यदि अभ्यर्थी सफल होता है तो न्यायालय उसे उसके अधिकारों को लागू कराने, क्षतिपूर्ति (damages) दिलवाने आदि का आदेश देता है।

A lawsuit is a proceeding by one or more parties against one or more parties in a civil court of law. The archaic term "suit in law" is found in only a small number of laws still in effect today. The term "lawsuit" is used with respect to a civil action brought by a plaintiff who requests a legal remedy or equitable remedy from a court. The defendant is required to respond to the plaintiff's complaint or else risk default judgment. If the plaintiff is successful, judgment is entered in favor of the defendant. A variety of court orders may be issued in connection with or as part of the judgment to enforce a right, award damages or restitution, or impose a temporary or permanent injunction to prevent an act or compel an act. A declaratory judgment may be issued to prevent future legal disputes.