Oscar, the owner of Blackacre in fee simple absolute, conveyed Blackacre “to Anna and her heirs insofar as the premises are not used for gambling, but if gambling ever occurs on the premises then Oscar shall reenter and terminate Annas ownership.
Anna built a restaurant and a banquet hall on the property 50 years ago. From the beginning of the banquet halls existence, each year a local high school rented the banquet hall for class reunions. At these reunions, bingo and poker games for cash prizes were part of the evening’s entertainment.
Oscar died last year. While Oscar was alive, Oscar never attempted to reclaim the property from Anna. Oscars will left all of Oscars property to a local charity. Oscars sole heir is Fred.
Your client wants to buy the property from Anna, tear down the restaurant and banquet hall, and build a neighborhood retail center instead. The retail center would include a convenience store that sells lottery tickets. 

Advise your client concerning the risks associated with acquiring title to the property, and how your client may attempt to mitigate these risks. In advising the client, assume that the statute of limitations for a possibility of reverter or a right of entry is 20 years, and that it is unclear whether or not the jurisdiction follows the common law rules for transferability of these future interests.

2-3 pages
Include Case Law if applicable