A more thorough explanation:

The intergovernmental-immunity doctrine is a principle in constitutional law that states that both the federal government and the states are independent sovereigns. This means that neither sovereign can interfere with the other in certain political spheres.

For example, if a state passes a law that conflicts with a federal law, the federal law will take precedence because of the intergovernmental-immunity doctrine. Similarly, if the federal government tries to interfere with a state's ability to govern itself, the state can claim immunity under this doctrine.

One example of the intergovernmental-immunity doctrine in action is the case of Nevada v. Hall. In this case, the Supreme Court ruled that states do not have immunity from lawsuits filed by individuals in other states. This decision was based on the idea that the intergovernmental-immunity doctrine does not apply in cases where a state is acting as a private party.

Another example is the case of Arizona v. United States. In this case, the Supreme Court ruled that certain provisions of Arizona's immigration law were preempted by federal law. This decision was based on the idea that the intergovernmental-immunity doctrine does not allow states to interfere with federal authority in certain areas, such as immigration.