Chicago v. Greer was a landmark Supreme Court case that established the principle of municipal immunity from tort liability. The case arose when a Chicago police officer, John Greer, was sued by a citizen for damages resulting from an alleged false arrest. Greer argued that the city of Chicago was immune from tort liability and that he should not be held personally liable for the damages. The Supreme Court agreed with Greer, ruling that the city of Chicago was immune from tort liability and that Greer could not be held personally liable for the damages. The Court reasoned that the city of Chicago was a public entity and that it was not responsible for the actions of its employees. The Court also noted that the city of Chicago had not waived its immunity from tort liability and that the citizen had not established a special relationship with the city that would have allowed him to sue for damages. The Court's ruling established the principle of municipal immunity from tort liability, which has been applied in numerous cases since then.

In the case of Chicago v. Greer, the Supreme Court was asked to decide whether a city ordinance that prohibited certain types of business from operating within its boundaries violated the Fourteenth Amendment's Equal Protection Clause. The majority opinion held that it did not, reasoning that cities have broad authority to regulate their own affairs and pass laws for their own benefit. However, Justice Field dissented on this point, arguing that while states may be able to enact such ordinances in order to protect public health or safety, they cannot do so if there is no rational basis for doing so or if it discriminates against particular classes of people without any legitimate purpose. He further argued that since the ordinance at issue here applied only to businesses owned by African Americans and not those owned by whites, it constituted an unconstitutional violation of equal protection under law as guaranteed by the Fourteenth Amendment.