Legal Question in Real Estate Law in California

The answer is kinda a "yes and no" proposition. In legal theory, when any real property is co-owned by two or more persons (whether as tenants in common, joint tenants or otherwise), any and all co-owners have an equal theoretical right to possess and occupy every square inch of the property at every moment, alnog with all other co-owners. This is one of the rights of a co-owner. Co-owners are, in effect, roommates. Of course, a co-owner can, and often does, give up such rights to a greater or lesser extent by contract.

In addition, there is another practical limitation on the right of a co-owner to immediate shared possession. An out-of-possession co-owner may need a court order to get back into possession if and when coming into possession peaceably may be difficult.

Therefore, the California Civil Code has a provision to help co-owners who have been "ousted" from possession to use the courts to regain (shared) possession. It's found at section 843, and it provides, basically, that the out-of-possession co-owner may make a formal written demand for "concurrent possession." The demand letter is served the same as a lawsuit, by a process server. If the co-owner in possession does not "offer and provide unconditional concurrent possession" within 60 days, an ouster is established and the out-of-possession co-owner can go to court and ask for damages or other relief, including help from the sheriff in regaining co-possession.

So, I guess the long and short of it is that you can keep your ex-wife out by keeping the doors locked, but ultimately if she wants in badly enough, she can cause you some legal problems using CC 843 procedures.

The ultimate weapon for unhappy co-owners of real property is not using 843 procedures or changing the locks or making threats or using the sheriff, however. There is another legal process called "partition," where one owner files and serves a special kind of lawsuit which asks the court to order the property sold and the net proceeds (after paying off the mortgage and other liens and costs of suit) divided fairly. In deciding what's "fair," the court is required to consider any excess expenditures of one co-owner for necessary costs such as mortgage payments, property taxes, insurance and needed maintenance.

I would recommend you consider bringing a partition action. This very likely will suggest to your ex-wife that she should negotiate with you for you to buy out her share -- what she would get from a partition -- without the hassle and expense of the suit.

If I had more information about the ownership and how you are still co-owning property after a divorce, maybe I could give you a more detailed response.