Defeasible fees (3 types)
1. Fee simple determinable (durational)
2. Fee simple subject to condition subsequent
3. Fee simple subject to executory interest
Fee simple determinable (durational)
always begins with phrase "O grants Blackacre to A and her heirs", always followed by 1 of these 4 phrases "for so long as", "while", "during", or "until"; if durational language is broken, then property goes back to grantors and his heirs through possibility of reverter (it's automatic)
Fee simple subject to condition subsequent
"O grants Blackacre to A and her heirs", and followed by "on condition that", "provided that", "however, if", "but if" - if conditional language is broken, O and O's heirs maintain a right of reentry back to the property; they have to exercise their right of reentry by i.e. filing action for ejectment (most common)
Fee simple subject to executory interest
"O grants to Blackacre to A and her heirs", can use either fee simple determinable or free simple subject to condition subsequent language; if language is broken, property doesn't go back to O, it goes to third party, B.B has executor interest and it is subject to RAP.
Restraint against alienation
restriction on free transferability of property; a direct restraint on a fee (to you, but if you ever try to sell it, you lose it - these are void as against public policy); Court cuts of "bad" part of conveyance and maintains flavor of the conveyance.