Short answer
A statute, ordinance, policy, order, or sign is not automatically constitutional because government adopted it.
Federal, state, and local government actions remain subject to constitutional review.
Viewpoint discriminationGovernment generally may not punish one viewpoint because officials dislike it.
Content-based restrictionsRules targeting what speech says usually face demanding constitutional scrutiny.
Content-neutral restrictionsSome rules concerning how, when, or where expression occurs can be lawful.
Forum doctrineThe legal test depends partly on the type of government property or forum involved.
CAP's question
When government says “there is a rule against it,” CAP asks the next question: Is that rule constitutional and lawful as applied here?