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 Montana, as in other states, various forms of legal immunity protect individuals and entities from civil liability or criminal prosecution. Judicial immunity in Montana shields judges from being sued for actions they take in their official capacity, ensuring that judges can perform their duties without fear of personal liability. Witness immunity is often granted to witnesses in criminal cases to encourage them to testify without fear of prosecution based on their testimony. Diplomatic immunity, governed by federal law and international treaties, protects foreign diplomats from legal action in the U.S. Lastly, governmental or sovereign immunity generally protects the state of Montana and its subdivisions from being sued without their consent, although this immunity can be waived in certain situations, such as through the Montana Tort Claims Act, which allows for some civil actions against the state or its employees for acts performed within the scope of their employment.