In the case of Donald Saucier v. Elliot M. Katz and In Defense of Animals, 2000, the U.S Supreme Court ruled in favor of a military police officer who was accused of using excessive force during an arrest at a public event. The plaintiff, Elliot Katz, claimed his First Amendment rights were violated when he was arrested for displaying a banner with political messages during Vice President Al Gore's speech on a military base in California. He also alleged that Officer Saucier used unnecessary force while detaining him which constituted as Fourth Amendment violation against unreasonable seizures. The court held that qualified immunity shields law enforcement officers from civil damages liability unless their actions violate clearly established statutory or constitutional rights which would be known by any reasonable official under similar circumstances. It further stated that even if there had been some degree of excessiveness in the use of force applied to detain Katz, it did not rise to the level necessary to constitute a clear violation under existing precedent.

In the dissenting opinion for Donald Saucier v. Elliot M. Katz and In Defense of Animals, Justice Stevens argued that the majority's decision to establish a new rule requiring courts to first determine whether an alleged constitutional right was clearly established at the time of violation before assessing its reasonableness is unnecessary and unwise. He contended that this approach complicates rather than simplifies matters, as it forces lower courts to engage in abstract legal analysis without considering specific facts of each case. Furthermore, he believed that this method could potentially shield officers from liability even when their actions were unreasonable by allowing them to argue lack of clear precedent on narrowly defined rights violations. Instead, Justice Stevens advocated for a more straightforward inquiry into whether or not an officer’s conduct was reasonable under existing law.