Wills Trusts and Estate Prof Blog reports on a Texas appellate court case in which a man referred to his wife's inheritance in two conflicting ways.  In one place the man referred to his wife receiving everything "until she dies" and in the other he stated he leaves her all his property. 

So -- which is it?  In life and in death the law doesn't generally allow you to give something to someone and then restrict what they do with it after they've received it.  Yes, you can do this if you give the gift in trust or you specify a charity must use its gift for a particular purpose.  A gift is a gift.  Contract law allows you to transfer something to someone with strings attached, but the exchange must be mutual and not a one-sided gift.  For example, I can write my contractor a check with the proviso that he must use it to buy materials for the deck he is building me, but then he has also promised to provide me with a deck.  I can't, however, give my brother a car and then demand that he must give it to his son if he ever tires of it.  Once my brother gets the car, it's his car to do with as he pleases. 

The Texas appellate court decided that the man who wrote the will meant to give his wife everything.  That may or may not be the case, but because he chose to write his will himself, the man assured there would be a court fight that disappointed someone enough to take it up on appeal.  That's an estate plan that didn't work.