Legal immunity from suit or liability (in civil litigation) or immunity from prosecution (in criminal prosecutions) is a legal status that protects an individual or entity from liability or criminal prosecution. Immunity may be given to the person or entity by law (usually a state or federal statute) or by the agreement of a party to the litigation (usually in the context of a criminal prosecution)—generally for some greater policy goal. Some common types of immunity include (1) judicial immunity; (2) witness immunity; (3) diplomatic immunity; and (4) governmental or sovereign immunity.

In Massachusetts, legal immunity encompasses various forms that protect individuals or entities from civil liability or criminal prosecution. Judicial immunity in MA shields judges from liability for acts performed in their judicial capacity, unless they acted in the clear absence of all jurisdiction. Witness immunity is provided to witnesses for testimony given in court, protecting them from being sued based on that testimony. Diplomatic immunity, governed by federal law and international treaties, applies to foreign diplomats and provides them with protection from civil and criminal jurisdiction of the host country's courts. Governmental or sovereign immunity in Massachusetts generally protects state and local government entities from being sued without their consent, although the Massachusetts Tort Claims Act allows for certain claims against the government under specific circumstances. Additionally, in criminal prosecutions, prosecutors may grant immunity to witnesses in exchange for testimony, which can either be transactional (complete immunity from prosecution for offenses related to the testimony) or use and derivative use immunity (preventing the prosecution from using the witness's testimony or any evidence derived from it in a case against the witness).