Civil procedure: Federal Rules of Civil Procedure: Pre-trial procedure

A lawsuit is a proceeding by a party or parties against another in the 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 in reference to a civil action brought by a plaintiff (a party who claims to have incurred loss as a result of a defendant's actions) requests a legal remedy or equitable remedy from a court. The defendant is required to respond to the plaintiff's complaint. If the plaintiff is successful, judgment is in the plaintiff's favor, and a variety of court orders may be issued to enforce a right, award damages, 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.

A lawsuit may involve dispute resolution of private law issues between individuals, business entities or non-profit organizations. A lawsuit may also enable the state to be treated as if it were a private party in a civil case, as plaintiff, or defendant regarding an injury, or may provide the state with a civil cause of action to enforce certain laws.

The conduct of a lawsuit is called litigation. The plaintiffs and defendants are called litigants and the attorneys representing them are called litigators. The term litigation may also refer to a criminal procedure.

Rules of procedure and complications.

Rules of criminal or civil procedure govern the conduct of a lawsuit in the common law adversarial system of dispute resolution. Procedural rules are constrained and informed by separate statutory laws, case laws, and constitutional provisions that define the rights of the parties to a lawsuit (see especially due process), though the rules generally reflect this legal context on their face. The details of the procedure differ greatly from jurisdiction to jurisdiction, and often from court to court even within the same jurisdiction. These rules of the particular procedures are very important for litigants to know, because the litigants are the ones who dictate the timing and progression of the lawsuit. Litigants are responsible to obtain the suited result and the timing of reaching this result. Failure to comply with the procedural rules may result in serious limitations that can affect the ability of one to present claims or defenses at any subsequent trial, or even promote the dismissal of the lawsuit altogether.

Though the majority of lawsuits are settled before ever reaching trial, they can still be very complicated to litigate. This is particularly true in federal systems, where a federal court may be applying state law (for example the Erie doctrine, for example in the United States), or vice versa. It is also possible for one state to apply the law of another in cases where additionally it may not be clear which level (or location) of court actually has jurisdiction over the claim or personal jurisdiction over the defendant, or whether the plaintiff has standing to participate in a lawsuit. About 98 percent of civil cases in the United States federal courts are resolved without a trial. Domestic courts are also often called upon to apply foreign law, or to act upon foreign defendants, over whom they may not even have the ability to even enforce a judgment if the defendant's assets are theoretically outside their reach.