A statute of limitations, known in civil law systems as a prescriptive period, is a law passed by a legislative body to set the maximum time after an event within which legal proceedings may be initiated. In most jurisdictions, such periods exist for both criminal law and civil law such as contract law and property law, though often under different names and with varying details.

When the time which is specified in a statute of limitations runs out, a claim may no longer be filed, or if filed, it may be subject to dismissal if the defense against that claim is raised that the claim is time-barred as having been filed after the statutory limitations period.

When a statute of limitations expires in a criminal case, the courts no longer have jurisdiction. In many jurisdictions with statutes of limitation there is no time limit for dealing with particularly serious crimes.

In civil law systems, such provisions are typically part of their civil and criminal codes. The cause of action dictates the statute of limitations, which can be reduced or extended in order to ensure a full and fair trial. The intention of these laws is to facilitate resolution within a "reasonable" period of time. What amount of time is considered "reasonable" varies from country to country. In some countries, as in the US, it may vary from jurisdiction to jurisdiction and state (or province, etc.) to state. Internationally, the statute of limitations may vary from one civil or criminal action to another. Some countries do not have a statute of limitations.

Analysis of a statute of limitations also requires the examination of any associated statute of repose, tolling provisions, and exclusions.

Common law legal systems can include a statute specifying the length of time within which a claimant or prosecutor must file a case. In some jurisdictions (e.g., California), a case cannot begin after the period specified, and courts have no jurisdiction over cases filed after the statute of limitations has expired. In some other jurisdictions (e.g., New South Wales, Australia), a claim can be filed which may prove to have been brought outside the limitations period, but the court will retain jurisdiction in order to determine that issue, and the onus is on the defendant to plead it as part of their defense, or else the claim will not be statute barred.

Once they are filed, cases do not need to be resolved within the period specified in the statute of limitations.

The purpose and effect of statutes of limitations are to protect defendants. There are three reasons for their enactment: