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 Illinois, legal immunity encompasses various forms that protect individuals or entities from civil liability or criminal prosecution. Judicial immunity in Illinois 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 for defamation based on their testimony. Diplomatic immunity is governed by federal law and international treaties, granting foreign diplomats certain protections from lawsuit and prosecution. Governmental or sovereign immunity in Illinois generally protects state government entities from being sued without their consent, but the Illinois Court of Claims Act allows for certain types of lawsuits against the state. Additionally, the Illinois Tort Immunity Act provides limited immunity to local governmental units and their employees when performing discretionary, rather than ministerial, functions. It's important to note that these immunities can have exceptions and specific conditions under which they apply, and they are often subject to interpretation by the courts.