What is the legal term for a claim that can support a lawsuit based on law and facts?

A cause of action refers to a legal reason or basis for which a party can file a lawsuit. It encompasses the facts and legal principles that give rise to the right to seek relief through the legal system. Each cause of action must present specific allegations that, if proven true, would justify a court in granting a remedy, such as damages or injunctions.

In legal contexts, a cause of action must establish both the legal framework (the law applicable to the situation) and the factual circumstances that support the claim. For example, in a personal injury lawsuit, the cause of action might be based on negligence, requiring proof of the defendant's duty of care, breach of that duty, causation, and resulting damages.

Looking at the other options, an affidavit is a written statement confirmed by oath or affirmation, typically used as evidence in legal proceedings. A caveat is a formal notice or warning, often in relation to probate law, and does not constitute a basis for a lawsuit. A testament usually refers to a legal document outlining a person's wishes regarding the distribution of their property upon death, commonly known as a will. Therefore, none of these terms provide the foundational legal basis for a lawsuit like a cause of action does.