Source: http://www3.ce9.uscourts.gov/jury-instructions/node/160
Timestamp: 2019-04-22 19:09:37+00:00

Document:
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.
Although the facts known to the officer are relevant to your inquiry, the officer’s intent or motive is not relevant to your inquiry.
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 9.3–9.8, and in conjunction with Instruction 9.20 (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." Lacey v. Maricopa County, 693 F.3d 896, 918 (9th Cir. 2012) (citation omitted). "Probable cause exists if the arresting officers had knowledge and reasonably trustworthy information of facts and circumstances sufficient to lead a prudent person to believe that [the arrestee] had committed or was committing a crime." Gravelet-Blondin v. Shelton, 728 F.3d 1086, 1097-98 (9th Cir. 2013)(alteration in original) (quoting Maxwell v. County of San Diego, 697 F.3d 941, 951 (9th Cir. 2012)). "To determine whether an officer had probable cause for an arrest, we examine the events leading up to the arrest, and then decide whether these historical facts, viewed from the standpoint of an objectively reasonable police officer, amount to probable cause. Because probable cause deals with probabilities and depends on the totality of the circumstances, it is a fluid concept that is not readily, or even usefully, reduced to a neat set of legal rules. It requires only a probability or substantial chance of criminal activity, not an actual showing of such activity. Probable cause is not a high bar." District of Columbia v. Wesby, 138 S.Ct. 577, 586 (2018) (internal quotations and citations omitted).
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) (emphasis in original); see also Tsao v. Desert Palace, Inc., 698 F.3d 1128, 1147 (9th Cir. 2012).
"There is probable cause for a warrantless arrest and a search incident to that arrest if, under the totality of the facts and circumstances known to the arresting officer, a prudent person would have concluded that there was a fair probability that the suspect had committed a crime." United States v. Struckman, 603 F.3d 731, 739 (9th Cir. 2010) (quoting United States v. Gonzales, 749 F.2d 1329, 1337 (9th Cir. 1984)). "If 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." Atwater v. City of Lago Vista, 532 U.S. 318, 354 (2001). "‘[S]tate restrictions [on arrest] do not alter the Fourth Amendment’s protections,’ and under federal law, ‘warrantless arrests for crimes committed in the presence of an arresting officer are reasonable under the Constitution.’" Edgerly v. City & County of San Francisco, 599 F.3d 946, 956 (9th Cir. 2010) (second alteration in original) (quoting Virginia v. Moore, 553 U.S. 164, 176 (2008)). A warrantless arrest for a crime committed in the presence of an arresting officer is permitted, even if the offense, as a matter of state law, was one for which the officers should have issued a summons rather than made an arrest. Moore, 553 U.S. at 167-72. 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 Hopkins v. Bonvicino, 573 F.3d 752, 773 (9th Cir. 2009).
"While the traditional Fourth Amendment analysis ‘is predominantly an objective inquiry,’ the ‘actual motivations’ of officers may be considered when applying the special needs doctrine." Scott v. City. of San Bernardino, 903 F.3d 943, 949 (9th Cir. 2018) (affirming summary judgment in favor of plaintiff middle school students unreasonably arrested without probable cause).

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