A police officer picked up a campaign sign featuring a candidate who was particularly unpopular in his department. Some of his co-workers spotted him and he got demoted the next day. But wait! It was all a big misunderstanding! He was actually just picking up the sign for his bed-ridden mother.
Generally, a First Amendment claim requires (1) protected speech; (2) a materially adverse action; and (3) a causal connection between the two. Here, it appears that the police office never really engaged in any "protected speech" because he was just picking up the sign for someone else.
Both the majority (by Justice Breyer) and the dissent (Justice Thomas) have logical arguments. Of course, it's the majority opinion that counts:
[T]he government’s reason for demoting [the police officer] is what counts here. When an employer demotes an employee out of a desire to prevent the employee from engaging in political activity that the First Amendment protects, the employee is entitled to challenge that unlawful action under the First Amendment and 42 U. S. C. §1983—even if, as here, the employer makes a factual mistake about the employee’s behavior.The counterargument, per Justice Thomas (joined by Justice Alito) in dissent:
Today the Court holds that a public employee may bring a federal lawsuit for money damages alleging a violation of a constitutional right that he concedes he did not exercise. Because federal law does not provide a cause of action to plaintiffs whose constitutional rights have not been violated, I respectfully dissent.The majority reversed the Third Circuit decision, which I covered here (embarrassingly declaring "game over"... not expecting SCOTUS review). I'm not sure how often this situation will arise in the future (my hunch is that it is pretty uncommon), but we will
know how to analyze it now.