A taking is not limited to formal condemnation. Where regulation deprives an owner of the use or value of property, compensation may be owed, and the owner’s route is an inverse condemnation claim — a suit by the owner rather than a proceeding by the government.
Categories that receive particular treatment: a permanent physical occupation, however small; and a regulation that deprives the property of all economically beneficial use, subject to background principles of property and nuisance law.
Everything else is assessed by weighing factors: the economic impact of the regulation, the extent to which it interferes with distinct investment-backed expectations, and the character of the governmental action. The analysis is notoriously fact-dependent and resists prediction.
Exactions. Conditions imposed on development permits — dedications of land, impact fees — must bear an essential nexus to a legitimate state interest and be roughly proportional to the impact of the proposed development. This is one of the more practically useful doctrines for a developer.
Procedure matters as much as substance. Ripeness requirements, notice-of-claim provisions and short limitations periods all apply, and claims are frequently lost on them. An owner facing a regulatory decision that destroys value should get advice about the deadline before pursuing further administrative remedies, not after.