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9.20 Particular Rights—Fourth Amendment—Unreasonable Seizure of Person—Probable Cause Arrest

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In general, a seizure of a person by arrest without a warrant is reasonable if the arresting officer[s] had probable cause to believe the plaintiff has committed or was committing a crime.

In order to prove the seizure in this case was unreasonable, the plaintiff must prove by a preponderance of the evidence that [he] [she] was arrested without probable cause.

"Probable cause" exists when, under all of the circumstances known to the officer[s] at the time, an objectively reasonable police officer would conclude there is a fair probability that the plaintiff has committed or was committing a crime.

Under [federal] [state] law, it is a crime to [insert elements or description of applicable crime for which probable cause must have existed].


Use this instruction only in conjunction with the applicable elements instructions, Instructions 9.2–9.7, and in conjunction with Instruction 9.18 (Particular Rights—Fourth Amendment—Unreasonable Seizure of Person—Generally).

"A claim for unlawful arrest is cognizable under § 1983 as a violation of the Fourth Amendment, provided the arrest was without probable cause or other justification." Dubner v. City and County of San Francisco, 266 F.3d 959, 964-65 (9th Cir.2001) (citing Larson v. Neimi, 9 F.3d 1397, 1400 (9th Cir.1993)).

In Devenpeck v. Alford, the Supreme Court reiterated the Fourth Amendment standards applicable in a § 1983 claim for false arrest:

The Fourth Amendment protects "[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures." In conformity with the rule at common law, a warrantless arrest by a law officer is reasonable under the Fourth Amendment where there is probable cause to believe that a criminal offense has been or is being committed. . . . Whether probable cause exists depends upon the reasonable conclusion to be drawn from the facts known to the arresting officer at the time of the arrest. . . .

Our cases make clear that an arresting officer’s state of mind (except for the facts that he knows) is irrelevant to the existence of probable cause. . . . That is to say, his subjective reason for making the arrest need not be the criminal offense as to which the known facts provide probable cause. As we have repeatedly explained, "the fact that the officer does not have the state of mind which is hypothecated by the reasons which provide the legal justification for the officer's action does not invalidate the action taken as long as the circumstances, viewed objectively, justify that action." . .. "[T]he Fourth Amendment’s concern with ‘reasonableness’ allows certain actions to be taken in certain circumstances, whatever the subjective intent."

Devenpeck v. Alford, 543 U.S. 146, 152–53 (2004) (citations omitted) (arresting officer’s subjective reason for making arrest need not be criminal offense for which known facts provide probable cause); see also Alford v. Haner, 446 F.3d 935 (9th Cir.2006) (opinion on rehearing after remand).

A police officer has probable cause to arrest a suspect without a warrant if the available facts suggest a "fair probability" that the suspect has committed a crime. Tatum v. City and County of San Francisco, 441 F.3d 1090, 1094 (9th Cir.2006) (citing United States v. Valencia-Amezcua, 278 F.3d 901, 906 (9th Cir.2002). See also Hart v. Parks, 450 F.3d 1059, 1066 (9th Cir.2006). "An officer who observes criminal conduct may arrest the offender without a warrant, even if the pertinent offense carries only a minor penalty." Tatum, 441 F.3d at 1094(quoting Atwater v. City of Lago Vista, 532 U.S. 318, 354 (2001) to the effect that "[i]f an officer has probable cause to believe that an individual has committed even a very minor criminal offense in his presence, he may, without violating the Fourth Amendment, arrest the offender."). Absent exigent circumstances, however, authority to make a warrantless arrest based on probable cause ends at the threshold of a private dwelling, and police may not make a warrantless, nonconsensual entry into a suspect’s residence to make a felony arrest. Payton v. New York, 445 U.S. 573, 590 (1980); see also United States v. Quaempts, 411 F.3d 1046, 1049 (9th Cir.2005).