206
Opinion of the Court
to refute respondent's claimed distinction between excessive force and other Fourth Amendment contexts; in both spheres the law must be elaborated from case to case. Qualified immunity operates in this case, then, just as it does in others, to protect officers from the sometimes "hazy border between excessive and acceptable force," Priester v. Riviera Beach, 208 F. 3d 919, 926-927 (CA11 2000), and to ensure that before they are subjected to suit, officers are on notice their conduct is unlawful.
Graham and Anderson refute the excessive force/probable cause distinction on which much of respondent's position seems to depend. The deference owed officers facing suits for alleged excessive force is not different in some qualitative respect from the probable-cause inquiry in Anderson. Officers can have reasonable, but mistaken, beliefs as to the facts establishing the existence of probable cause or exigent circumstances, for example, and in those situations courts will not hold that they have violated the Constitution. Yet, even if a court were to hold that the officer violated the Fourth Amendment by conducting an unreasonable, warrantless search, Anderson still operates to grant officers immunity for reasonable mistakes as to the legality of their actions. The same analysis is applicable in excessive force cases, where in addition to the deference officers receive on the underlying constitutional claim, qualified immunity can apply in the event the mistaken belief was reasonable.
The temporal perspective of the inquiry, whether labeled as ex ante or ex post, offers no meaningful distinction between excessive force and other Fourth Amendment suits. Graham recognized as much, reviewing several of our probable-cause and search warrant cases, then stating that "[w]ith respect to a claim of excessive force, the same standard of reasonableness at the moment applies." 490 U. S., at 396 (discussing use of force under Terry v. Ohio, 392 U. S. 1 (1968); probable cause to arrest under Hill v. California, 401 U. S. 797 (1971); and search warrant requirements under
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