What is Cause Of Action?

Legal Definition
In the law, a cause of action is a set of facts sufficient to justify a right to sue to obtain money, property, or the enforcement of a right against another party. The term also refers to the legal theory upon which a plaintiff brings suit (such as breach of contract, battery, or false imprisonment). The legal document which carries a claim is often called a Statement of Claim in English law, or a Complaint in U.S. federal practice and in many U.S. states. It can be any communication notifying the party to whom it is addressed of an alleged fault which resulted in damages, often expressed in amount of money the receiving party should pay/reimburse.

To pursue a cause of action, a plaintiff pleads or alleges facts in a complaint, the pleading that initiates a lawsuit. A cause of action generally encompasses both the legal theory (the legal wrong the plaintiff claims to have suffered) and the remedy (the relief a court is asked to grant). Often the facts or circumstances that entitle a person to seek judicial relief may create multiple causes of action. Although it is fairly straightforward to file a Statement of Claim in most jurisdictions, if it is not done properly, then the filing party may lose his case due to simple technicalities.

There are a number of specific causes of action, including: contract-based actions; statutory causes of action; torts such as assault, battery, invasion of privacy, fraud, slander, negligence, intentional infliction of emotional distress; and suits in equity such as unjust enrichment and quantum meruit.

The points a plaintiff must prove to win a given type of case are called the "elements" of that cause of action. For example, for a claim of negligence, the elements are: the (existence of a) duty, breach (of that duty), proximate cause (by that breach), and damages. If a complaint does not allege facts sufficient to support every element of a claim, the court, upon motion by the opposing party, may dismiss the complaint for failure to state a claim for which relief can be granted.

The defendant to a cause of action must file an "Answer" to the complaint in which the claims can be admitted or denied (including denial on the basis of insufficient information in the complaint to form a response). The answer may also contain counterclaims in which the "Counterclaim Plaintiff" states its own causes of action. Finally, the answer may contain affirmative defenses. Most defenses must be raised at the first possible opportunity either in the answer or by motion or are deemed waived. A few defenses, in particular a court's lack of subject matter jurisdiction, need not be pleaded and may be raised at any time.
-- Wikipedia
Legal Definition
A set of predefined factual elements that allow for a legal remedy. The factual elements needed for a specific cause of action can come from a constitution, statute, judicial precedent, or administrative regulation.

See Claim and Civil procedure.
Legal Definition
By this phrase is understood the right to bring an action, which implies, that there is some person in existence who can assert, and also a person who can lawfully be sued; for example, where the payee of a bill was dead at the time when it fell due, it was held the cause of action did not accrue, and consequently the statute of limitations did not begin to run until letters of administration had been obtained by some one. 4 Bing. 686.

2. There is no cause of action till the claimant can legally sue, therefore the statute of limitations does not run from the making of a promise, if it were to perform something at a future time, but only from the expiration of that time, though, when the obligor promises to pay on demand, or generally, without specifying day, he may be sued immediately, and then the cause of action has accrued. 5 Bar. & Cr. 860; 8 Dowl. & R. 346.When a wrong has been committed, or a breach of duty has occurred, the cause of action has accrued, though the claimant may be ignorant of it. 3 Barn. & Ald. 288, 626 5 B. & C. 259; 4 C. & P. 127.
-- Bouviers Law Dictionary
Legal Definition
Matter for which an action may be brought. The ground on which an action may be sustained. The right to bring a suit. Cause of action is properly the ground on which an action can be maintained; as when wesay that such a person has no cause of action. But the phrase is often used to signify the matter of the complaint or claim on which a given action is in fact grounded, whether or not legally maintainable. Moziey & Whitley. It sometimes means a person having a right of action. Thus, where a legacy is left to a married woman, and she and her husband bring an action to recover it, she is called in the old books the "meritorious cause of action." 1 H. Bl. 108. The term is synonymous with right of action, right of recovery. Graham v. Scripfure, 26 How. Prae. (N. Y.) 501. Cause of action is not synonymous with chose in action; the latter includes debts, etc., not due, and even stocks. Bank of Commerce v. Rutland & W. R. Co., 10 How. Prac. (N. Y.) i.
-- Black's Law Dictionary
Legal Definition
A right to sue.
-- Ballentine's Law Dictionary