Government regulation may so burden property that compensation is required though no title has been taken.
Per se takings. A permanent physical occupation, however minor, and a regulation depriving property of all economically beneficial use. The latter is subject to an exception where the restriction inheres in background principles of state property and nuisance law.
The multifactor test for everything else weighs the economic impact of the regulation, the extent to which it interferes with distinct investment-backed expectations, and the character of the government action.
The denominator problem. Whether impact is measured against the affected portion or the whole parcel frequently decides the case, and courts consider the treatment of the land under state law, its physical characteristics and its value.
Exactions are assessed under the nexus and proportionality standards.
Ripeness. A claim generally requires a final decision from the regulating body about the permitted use. Property owners must pursue a meaningful application and, in many cases, a variance before suing. A state compensation procedure need not be exhausted first.
Temporary takings. A regulation later invalidated may still require compensation for the period it was in force.
Practical municipal guidance. Build a record of the economic analysis and the alternatives considered before adopting regulation that materially restricts identified parcels.