A public employer or official may not take adverse action against a person because of constitutionally protected speech. The elements are straightforward and the proof is not.

Protected activity. For a public employee, speech on a matter of public concern made as a citizen rather than pursuant to official duties, with the employer’s interest in efficient operation weighed against the speech interest. For a citizen, speech that is protected under ordinary principles.

Adverse action. Conduct that would deter a person of ordinary firmness. This is broader than employment consequences and can include denial of permits, selective enforcement, and exclusion from meetings.

Causation. The speech must be a substantial or motivating factor. The employer may then show it would have taken the same action regardless. Temporal proximity, deviation from practice, and statements by decision-makers are the usual evidence.

Retaliatory prosecution and arrest claims generally require the absence of probable cause, subject to a narrow exception where objective evidence shows that similarly situated individuals not engaged in the speech were not subjected to the same treatment.

Municipal practice. Officials frustrated by a persistent critic should document that enforcement decisions follow ordinary practice and are made by people without a stake in the dispute. Selective enforcement against a known critic is the archetype of this claim.