The requirement that an arrest for a misdemeanor have occurred in the officer’s presence is a statutory rule [I thought common law], but not a Fourth Amendment requirement. Here, the officer still had probable cause, but didn’t see it. Not a Fourth Amendment violation. Vanegas v. City of Pasadena, 2022 U.S. App. LEXIS 24544 (9th Cir. Aug. 31, 2022):
There is one wrinkle. Violation of § 415(2) is a misdemeanor. See Cal. Penal Code § 17(b). Under California law, an officer may only make a warrantless arrest for a misdemeanor if he has probable cause to believe that the person committed the offense in the officer’s presence. Cal. Penal Code § 836(a)(1). So if Vanegas’s arrest was based on § 415(2), then the officers may have violated California law because his conduct was not in Officer Klotz’s presence. But that does not change the result. That’s because “[t]he requirement that a misdemeanor must have occurred in the officer’s presence to justify a warrantless arrest is not grounded in the Fourth Amendment.” Barry v. Fowler, 902 F.2d 770, 772 (9th Cir. 1990). So to establish a violation of the Fourth Amendment, it does not matter if Officer Klotz was present when Vanegas committed the misdemeanor. Rather, the “crucial inquiry” is whether Officer Klotz had probable cause to make the arrest. Id. at 773. Here, we hold that he did.
Having found no violation of the Fourth Amendment, we need not proceed to the second question of whether the officers violated a “clearly established” right for Vanegas’s offense under § 415(2). So on this basis alone, Officer Klotz lawfully arrested Vanegas.