Defeasible fees allow a grantor to control the grantee’s use of the property by placing some condition on the grantee’s possession. While restraints on use are valid, absolute restraints on the grantee’s ability to sell the land are void because the law favors alienability. Defeasible fees can be passed on by will or intestacy (i.e., they are devisable and descendible), and they do require magic words signifying some duration, like “so long as,” “while,” “until,” or “but if.” Two kinds of defeasible fees—fee simple determinable and fee simple subject to condition subsequent—create future interests in the grantor. The third kind—fee simple subject to an executory interest—creates a future interest in a third party.

This grant contains the magic words that signal it is a fee simple subject to condition subsequent: “but if.” In this type of present estate, the grantor retains the right to reenter—also called the power of termination—if the grantee violates the condition. But the right to reenter is merely an option. Alice doesn’t lose her interest automatically; Owen could either exercise his option or choose to overlook Alice’s violation. The rule against perpetuities does not apply to fees simple subject to condition subsequent because they create a future interest in the grantor.