What is probable cause for arrest without probable cause?

An arrest without probable cause violates the Fourth Amendment and gives rise to a claim for damages under section 1983. Harper v. City of Los Angeles, 533 F.3d 1010, 1022 (9th Cir. 2008). "Probable cause to arrest exists when officers have knowledge or reasonably trustworthy information sufficient to lead a person of reasonable caution to believe an offense has been or is being committed by the person being arrested." Id. (internal quotation marks omitted) (quoting United States v. Lopez, 482 F.3d 1067, 1072 (9th Cir. 2007)). While conclusive evidence of guilt is not required, "[m]ere suspicion, common rumor, or even strong reason to suspect are not enough" to establish probable cause. Id. (citation and internal quotation marks omitted).

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