Democracy in America can only work when members of the public are free to participate in the political process. That’s exactly what Fane Lozman was trying to do when a Riviera Beach, Florida, city official ordered him arrested 11 years ago.

Lozman sued the city, arguing that his arrest was in retaliation to his First Amendment-protected criticism of city policies and corruption. Before this arrest, city council members were on record suggesting “intimidating” him due to his opposition of the city’s redevelopment plan. The city had also made Lozman “the target of a string of legal pressures,” including attempting to evict him from the local marina (which a jury found to be retaliation for Lozman’s First Amendment expression), arresting and removing him from a different council meeting, and much more.

Despite all that, the U.S. Court of Appeals for the Eleventh Circuit ruled that Lozman was barred from suing the city because there may have been probable cause for his arrest, and further that the existence of probable cause categorically barred a claim for retaliatory arrest. What’s worse is that the crime for which “probable cause” the city relies on—“disturbance of a lawful assembly”—wasn’t mentioned or identified until trial eight years later.

The Supreme Court agreed to hear the case. Because a categorical bar on First Amendment retaliation claims for arrests supported by probable cause would deal a serious blow to our First Amendment freedoms, Cato joined the Institute for Justice on an amicus brief supporting Lozman. Under the lower court’s approach, courts would be forbidden from looking into the government’s motives in retaliatory-arrest cases the way they do with ease in other First Amendment retaliation cases. This would encourage local governments simply to arrest dissenters, knowing endless justifications could be manufactured after the fact and virtually eliminating any constitutional check on their retaliation.

For example, the offense that was ultimately claimed as the basis for Lozman’s arrest—“disturbing a lawful assembly”—requires only that one act with reckless disregard for whether one’s conduct will “impede the successful functioning of the assembly.” That vagueness could include anyone who speaks passionately at a public meeting. The result is to insulate arresting officials from liability even where, as here, the circumstances of the arrest strongly indicate a retaliatory motive.

Whether your First Amendment rights are protected should not be predicated on how the government infringes them, but that is the result of requiring judges and juries to close their eyes to the reasons for arrests. In these cases, there’s no reason to keep a jury from assessing that motivation and holding the government liable if the arrest was in retaliation for protected speech.

Retaliation forces the intolerable choice of speaking out and facing personal jeopardy or keeping silent. Faced with that choice, all but the most courageous will keep quiet—undermining the “uninhibited, robust, and wide-open” debate on public issues that the First Amendment protects. If the Supreme Court lets the lower court’s decision stand, local governments seeking to silence political activists will be empowered to abuse them.