Legal Question in Real Estate Law in California

Generally, vested interests in property can be bought and sold. It is possible that a vested interest could be created so that it was truly personal, and an attempt to sell it would either be void or would terminate the vesting so the interest would cease to exist, such as a tenant's vested but non-assignable interest under a lease. Being vested in a property merely means having some cognizable interest in it, which can be as a 100% owner in fee, down to having a fractional interest as one of several remaindermen after a life tenancy ends. Unfortunately, it's pretty hard to define without using other rather technical terms.

A good example might be as follows. Dad puts son in his will to receive the family farm, Blackacre. Son doesn't have a vested interest in Blackacre at this point; what he has is called an "expectation," or sometimes, a "mere expectation" to emphasize that he has no vested interest. This is because Dad can change his will any time up until he dies. When Dad dies, the will is read, and it turns out Dad gave Blackacre to the Little Sisters of Charity, subject to their never using it as a brothel or distillery. The will further provides that if they do, they lose title and Son gets it. Son now has a vested interest in Blackacre, because it is subject to a reversion to him, but he is not an owner.

In your example, A can sell to X, but X will only get whatever right, title and interest A held at the time of sale. If B also has some interest in the property, he can sell to anyone (assuming his interest is sellable), including A, X, or Y or Z. If B sold to A, this would raise another interesting question -- whether X automatically gets this "after-acquired interest" as a result of the earlier conveyance from A to X. I once knew the answer to this, but would have to research it.

Because there are so many different ways in which vested interests can be created, you should probably consult with a real estate lawyer with whom you can share all the particulars before deciding whether your is transferable and what its approximate value might be.

Apurtanent easements are vested and cannot be independently sold, so Mr. Whipple's answer is not entirely correct. There is no way to answer your question properly without knowing what interest is vested. "Vested" is not a right or bundle of rights. Ownership is a label for a bundle of rights; ownership is a vested interest. So you cannot compare "owns" and "vested." You compare vested with contingent. If I put in my will that you get my house to live in for your lifetime, and then it goes to my nephew if he is alive when I die, and to charity if he is not, you each have a contingent interest - both contingent on outliving me. If you both outlive me, your contingent interests then become vested interests. My nephew becomes vested owner, subject to your vested life estate. There are millions of other ways there can be contingent and vested interests, but the one thing that is always true is that "vested" describes the status of an interest. Without knowing what interest B has that is "vested," there is no way to answer your question.