Sovereign immunity (also known as governmental immunity) in American law was derived from the British common law doctrine that the King could do no wrong—and thus could not be sued. Sovereign immunity varies from state to state, but typically applies to state governments as well as the federal government.

But federal and state governments (generally the U.S. Congress and state legislatures) have the ability to waive their sovereign immunity. Waivers of sovereign immunity are usually included in state and federal statutes, and interpreted and applied by state and federal courts in court opinions.

For example, sovereign immunity protects the state and its various provisions of state government—including agencies, boards, hospitals, and universities—from liability and from suit—unless the immunity has been waived. Similarly, sovereign immunity protects political subdivisions—including counties, cities, and school districts—from liability and from suit—unless the immunity has been waived.

Thus, sovereign immunity encompasses two principles: (1) immunity from suit and (2) immunity from liability. Immunity from suit bars a suit against the state or other governmental entity unless the Legislature expressly gives consent. Immunity from liability protects the state or other governmental entity from judgments even if the Legislature has expressly given consent to sue.

In some states, when a governmental entity contracts, it is liable on contracts made for its benefit as if it were a private person. Consequently, when a governmental entity contracts with private citizens it waives immunity from liability. But the governmental entity does not waive immunity from suit simply by contracting with a private person. Legislative consent to sue is still necessary.

A party may establish legislative consent by referencing a statute or a resolution granting express legislative permission. Legislative consent to sue the state or other governmental entity must be expressed in clear and unambiguous language.

In Illinois, sovereign immunity is a legal doctrine that protects the state government, its agencies, and political subdivisions from being sued or held liable in court without their consent. This immunity extends to various state entities, including agencies, boards, hospitals, universities, counties, cities, and school districts. However, the state can waive this immunity through legislation. The Illinois Court of Claims is the venue where claims against the state are typically heard, as the state has consented to be sued in this court for certain types of claims. The Illinois General Assembly has the authority to waive sovereign immunity by passing statutes that allow for such lawsuits. For example, the Illinois Court of Claims Act and the State Lawsuit Immunity Act are examples of legislation that address the state's sovereign immunity. It's important to note that even when the state contracts with private parties, it does not automatically waive its immunity from suit; explicit legislative consent is still required. Additionally, while the state may be liable on contracts as a private individual would be, this does not negate the need for legislative consent to bring a lawsuit against the state or its entities.