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 Pennsylvania, sovereign immunity is a legal doctrine that protects the state government, including its agencies, boards, hospitals, and universities, from being sued or held liable in court, unless this immunity has been explicitly waived by statute. The Pennsylvania General Assembly has the authority to waive sovereign immunity, and such waivers are typically found in state statutes. The Commonwealth of Pennsylvania has enacted the Sovereign Immunity Act, which provides specific instances where the state has waived its immunity and can be sued, such as in cases of vehicle liability, medical-professional liability, and care, custody, or control of personal property, among others. However, even with these waivers, there are often limitations on the amount of damages that can be recovered. Additionally, political subdivisions such as counties, cities, and school districts also enjoy a level of sovereign immunity, which can be waived under certain circumstances as outlined in the Political Subdivision Tort Claims Act. It's important to note that while a governmental entity may be liable on contracts made for its benefit as if it were a private person, this does not necessarily waive immunity from suit; explicit legislative consent is still required for a lawsuit to proceed.