The City resists the applicability of the Mt. Healthy test as the sole determinant here. It contends that, where there was probable cause for the arrest, the applicable precedent is Hartman—a case that was in the criminal sphere and that turned on the existence of probable cause.
The background in Hartman was that a company and its chief executive, William Moore, had engaged in an extensive lobbying and governmental relations campaign opposing a particular postal service policy. 547 U.S., at 252–253. Moore and the company were later prosecuted for violating federal statutes in the course of that lobbying. Id., at 253–254. After being acquitted, Moore filed suit against five postal inspectors, alleging that they had violated his First Amendment rights when they instigated his prosecution in retaliation for his criticisms of the Postal Service. Id., at 254. This 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: The plaintiff must show that the retaliation was a substantial or motivating factor behind the prosecution, and, if that showing is made, the defendant can prevail only by showing that the prosecution would have been initiated without respect to retaliation. See 547 U.S., at 265–266.
The Court in Hartman deemed it necessary to inquire as to the existence of probable cause because proving the link between the defendant’s retaliatory animus and the plaintiff’s injury in retaliatory prosecution cases “is usually more complex than it is in other retaliation cases.” Id., at 261. An action for retaliatory prosecution “will not be brought against the prosecutor, who is absolutely immune from liability for the decision to prosecute.” Id., at 261–262. Instead, the plaintiff must sue some other government official and prove that the official “induced the
