Legal Question in Real Estate Law in California

While you may argue about the right to possession, I would suggest you consider a partion action in which you move to force a sale of the house and a division of the sale proceeds. From your description, it would appear the relationship has deteriorated to the point that co ownership is unlikely to be a viable option. Seek counsel as to how to proceed. With luck and a good lawyer perhaps you can work out a voluntary sale and division rather than having a long court battle.

When you say you are both "on the deed," I assume you mean you are both "on title." A deed is a one-shot document used to transfer ownership, and once title is transferred and recorded, the deed becomes more or less wastepaper. In any case, what is going on (where one owner is kicked out or excluded from co-possession by the other) is termed an "ouster" and is partially addressed in the Civil Code at section 843.

The law basically gives you three options, which are not necessarily exclusive of one another. You can sue for money damages, for restoration of possession (probably via asking for an injunction against interference with your right of co-possession), or for partition. Partition is a court-ordered sale of the property, after which the net proceeds of sale are divided between the former co-owners, with the court supervising all this so that the money gets divided fairly, taking into account money spent by each former owner for costs and expenses such as mortgage principal and interest, insurance, property taxes and necessary repairs.

Partition suits can get complicated and expensive, but lawyers often recommend them to unhappy co-owners because of the finality of the result and the fact that many such suits are settled out-of-court once the defendant sees the handwriting on the wall. Sometimes such an out-of-court settlement agreement in a partition suit will involve and agreement to use an arbitrator to decide any issues the warring co-owners cannot agree upon, such as which costs and expenses should be shared and which didn't benefit the other party at all.