delivered the opinion of the Court.
This case presents the question whether an arrest is lawful under the Fourth Amendment when the criminal offense for which there is probable cause to arrest is not “closely related” to the offense stated by the arresting officer at the time of arrest.
I
A
On the night of November 22,1997, a disabled automobile and its passengers were stranded on the shoulder of State Route 16, a divided highway, in Pierce County, Washington.
Alford
v.
Haner,
On the basis of this information, Haner radioed his supervisor, Sergeant Gerald Devenpeck, the other petitioner here, that he was concerned respondent was an “impersonator”
*149
or “wannabe cop.”
Id.,
at 97-98. He pursued respondent’s vehicle and pulled it over.
Sergeant Devenpeck arrived on the scene a short time later. After Haner informed Devenpeck of the basis for his belief that respondent had been impersonating a pólice officer,
id.,
at 110, Devenpeck approached respondent’s vehicle and inquired about the wig-wag headlights,
A short time later; Devenpeck reached by phone Mark Lindquist, a deputy county prosecutor, to whom he recounted the events leading to • respondent’s arrest.
At booking, Haner charged respondent with violating the State Privacy Act, id., at 32-33, and issued a ticket to respondent for his flashing headlights under Wash. Rev. Code §46.37.280(3) (1994), App. 24-25. Under state law, respondent could be detained on the latter offense only for the period of time “reasonably necessary” to issue a citation. *151 §46.64.015. The state trial court subsequently dismissed both charges. App. 10, 29.
B
Respondent filed suit against petitioners in Federal District Court. He asserted a federal cause of action under Rev. Stat. § 1979, 42 U. S. C. § 1983, and a state cause of action for unlawful arrest and imprisonment, both claims resting upon the allegation that petitioners arrested him without probable cause in violation of the Fourth and Fourteenth Amendments.
*152
A divided panel of the Court of Appeals for the Ninth Circuit reversed, finding “no evidence to support the jury’s verdict,”
HH HH
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. See
United States
v.
Watson,
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. See
Whren
v.
United States,
The rule that the. offense establishing probable cause must be “closely related” to, and based on the same conduct as, the offense identified by the arresting officer at the time of arrest is inconsistent with this precedent.
2
Such a rule
*154
makes the lawfulness of an arrest turn upon the motivation of the arresting officer — eliminating, as validating probable cause, facts that played no part in the officer’s expressed subjective reason for making the arrest, and offenses that are not “closely related” to that subjective reason. See,
e. g., Sheehy
v.
Plymouth,
Those who support the “closely related offense” rule say that, although it is aimed at rooting out the subjective vice of arrests made for the wrong reason, it does so by objective means — that is, by reference to the arresting officer’s statement of his reason. The same argument was made in Whren, supra, in defense of the proposed rule that a traffic stop can be declared invalid for malicious motivation when it is justified only by an offense which standard police practice does not make the basis for a stop. That rule, it was said, “attempt[s] to root out subjective vices through objective means,” id., at 814. We rejected the argument there, and we reject it again here. Subjective intent of the arresting officer, however it is determined (and of course subjective intent is always determined by objective means), is simply *155 no basis for invalidating an arrest. Those are lawfully arrested whom the facts known to the arresting officers give probable cause to arrest.
Finally, the “closely related offense” rule is condemned by its perverse consequences. While it is assuredly good police practice to inform a person of the reason for his arrest at the time he is taken into custody, we have never held that to be constitutionally required. 3 Hence, the predictable consequence of a rule limiting the probable-cause inquiry to offenses closely related to (and supported by the same facts as) those identified by the arresting officer is not, as respondent contends, that officers will cease making sham arrests on the hope that such arrests will later be validated, but rather that officers will cease providing reasons for arrest. And even if this option were to be foreclosed by adoption of a statutory or constitutional requirement, officers would simply give every reason for which probable cause could conceivably exist.
The facts of this case exemplify the arbitrary consequences of a “closely related offense” rule. Officer Haner’s initial stop of respondent was motivated entirely by the suspicion that he was impersonating a police officer. App. 106. Before pulling respondent over, Haner indicated by radio that this was his concern; during the stop, Haner asked respondent whether he was actively employed in law enforcement and why his car had wig-wag headlights; and when Sergeant Devenpeck arrived, Haner told him why he thought respondent was a “wannabe cop,”
id.,
at 98. In addition, in the course of interrogating respondent, both officers became convinced that he was not answering their questions truthfully and, with respect to the wig-wag headlights, that he
*156
was affirmatively trying to mislead them. Only after these suspicions had developed did Devenpeck discover the taping, place respondent under arrest, and offer the Privacy Act as the reason. Because of the “closely related offense” rule, Devenpeck’s actions render irrelevant both Haner’s developed suspicions that respondent was impersonating a police officer and the officers’ shared belief that respondent obstructed their investigation. The outcome under the “closely related offense” rule might well have been different if Haner, rather than Devenpeck, had made the arrest, on the stated basis of
his
suspicions; if Devenpeck had not abided the county’s policy against stacking charges; or if either officer had made the arrest without stating the grounds. We have consistently rejected a conception of the Fourth Amendment that would produce such haphazard results. See
Whren,
* * *
Respondent contended below that petitioners lacked probable cause to arrest him for obstructing a law-enforcement officer or for impersonating a law-enforcement officer. Because the Court of Appeals held that those offenses were legally irrelevant, it did not decide the question. We decline to engage in this inquiry for the first time here. Accordingly, we reverse the judgment of the Ninth Circuit and remand the case for further proceedings consistent with this opinion.
It is so ordered.
Notes
The relevant provision of the Washington Privacy Act states:
“Except as otherwise provided in this chapter, it shall be unlawful for any individual, partnership, corporation, association, or the state of Washington, its agencies, and political subdivisions to intercept, or record any . . . [p]rivate conversation, by any device electronic or otherwise designed to record or transmit such conversation regardless how the device is powered or actuated without first obtaining the consent of all the persons engaged in the conversation.” Wash. Rev. Code § 9.78.030(1)(b) (1994).
At least one Court of Appeals has adopted a variation of the “closely related offense” rule which looks not to the offense stated by the officer at the time of arrest, but to the offense given by the officer at booking. See
Gassner
v.
Garland,
Even absent a requirement that an individual be informed of the reason for arrest when he is taken into custody, he will not be left to wonder for long. “[Pjersons arrested without a warrant must promptly be brought before a neutral magistrate for a judicial determination of probable cause.”
County of Riverside
v.
McLaughlin,
