What is a type of fee simple defeasible estate that automatically reverts to the original owner if deed requirements are violated?

A fee simple determinable is a specific type of defeasible estate characterized by its automatic reversion to the original owner if certain conditions, specified in the deed, are not met. This means that as long as the conditions stipulated in the deed are adhered to, the owner retains the property indefinitely. However, should a violation occur, ownership instantly and automatically reverts to the grantor or their heirs without the need for any legal action.

This concept hinges on the unique language used in the deed, often including phrases such as "as long as" or "until," which establish the conditions under which the property can be held. This differentiates it from other types of estates, as it ensures a direct and immediate course of action (the reversion) upon violation of the specified deed conditions. In contrast, options such as fee simple absolute do not include these conditions and therefore do not revert automatically, while life estates and fee simple conditional estates involve different rules for reversion and are governed by distinct legal principles.