returned a verdict for the City on all of the claims. The District Court instructed the jury that, for Lozman to prevail on his claim of a retaliatory arrest at the city council meeting, he had to prove that the arresting officer was motivated by impermissible animus against Lozman’s protected speech and that the officer lacked probable cause to make the arrest. The Eleventh Circuit affirmed, concluding that any error the District Court made when it instructed the jury to consider the officer’s retaliatory animus was harmless because the jury necessarily determined that the arrest was supported by probable cause when it found for the City on Lozman’s other claims. The existence of probable cause, the court ruled, defeated a First Amendment claim for retaliatory arrest.
Held: The existence of probable cause does not bar Lozman’s First Amendment retaliation claim under the circumstances of this case. Pp. 5–13.
(a) The issue here is narrow. Lozman concedes that there was probable cause for his arrest. Nonetheless, he claims, the arrest violated the First Amendment because it was ordered in retaliation for his earlier, protected speech: his open-meetings lawsuit and his prior public criticisms of city officials. Pp. 5–6.
(b) In a §1983 case, a city or other local governmental entity cannot be subject to liability unless the harm was caused in the implementation of “official municipal policy.” Monell v. New York City Dept. of Social Servs., 436 U. S. 658, 691. The Court assumes that Lozman’s arrest was taken pursuant to an official city policy.
Two major precedents bear on the issue whether the conceded existence of probable cause for the arrest bars recovery regardless of any intent or purpose to retaliate for past speech. Lozman argues that the controlling rule is found in Mt. Healthy City Bd. of Ed. v. Doyle, 429 U. S. 274, a civil case in which a city board of education decided not to rehire an untenured teacher after a series of incidents, including a telephone call to a local radio station. The phone call was protected speech, but, the Court held, there was no liability unless the alleged constitutional violation was a but-for cause of the employment termination. Id., at 285–287. The City counters that the applicable precedent is Hartman v. Moore, 547 U. S. 250, where the Court held that a plaintiff alleging a retaliatory prosecution must show the absence of probable cause for the underlying criminal charge, id., at 265–266. If there was probable cause, the case ends. If the plaintiff proves the absence of probable cause, then the Mt. Healthy test governs. Pp. 6–10.
(c) Whether Hartman or Mt. Healthy governs here is a determination that must await a different case. For Lozman’s claim is far afield from the typical retaliatory arrest claim, and the difficulties
