Disputes about local government authority are usually resolved by construing the charter or an ordinance, applying settled interpretive principles.
Plain meaning. If the language is unambiguous, it is applied as written. Terms are given their ordinary meaning unless defined or technical.
Whole text. Provisions are read together so that each has effect, and a reading rendering a provision meaningless is disfavoured.
Specific over general, and later-enacted over earlier where they conflict.
Expressio unius. The expression of one thing implies the exclusion of others, applied cautiously to lists that appear illustrative.
Grants of power. Home rule jurisdictions generally construe municipal powers broadly, subject to constitutional and statutory limits. In jurisdictions following the narrower approach, a municipality has only powers expressly granted, necessarily implied, or essential to its declared purposes, and doubts are resolved against the power.
Preemption. State law may preempt expressly, by occupying the field, or by conflict. A local ordinance that permits what the state prohibits, or prohibits what the state permits as of right, is vulnerable.
Administrative construction by the officials who apply the ordinance receives some weight, particularly where longstanding and consistent.
Practical implication. Where authority is doubtful, an opinion before adoption costs far less than a challenge afterwards.