Legal Question in Wills and Trusts in California

Any co-owner can petition the court to "partition" the property by selling the property at auction, which will fetch a far lower price than would an ordinary sale. In other words, this would be against the economic self-interest of whomever files the petition. Search [prisoners dilemma].

It depends in part on how title is held, but if none of them is married to another and each holds an undivided 1/3 share as Tenants in Common or Joint Tenants, then A can definitely sell their share without the consent of B and/or C, IF A can find a buyer. Unless the property is a multi-unit dwelling that has been structured as Tenants in Common to work around condo conversion limitations, or it is an investment property and B and C cooperate in the sale, there is little or no market for a fractional share in a property. So finding a buyer is a BIG IF. The other alternative as Mr. Stone says is a court action for Partition. In the dim past of large estates, the courts could literally partition the property into separate parcels when co-owners could not agree on the use or disposal of the property. With modern subdivision laws, however, that is no longer possible, so the court must partition by sale and divide the proceeds. As Mr. Stone notes, that is usually an economically losing proposition for all the owners. So partition realistically is a tool to force a negotiation to either market the property amicably and divide the proceeds or for the owners who want to keep the property to buy out the one who wants out. If the parties cannot agree, however, the only thing the court can do is force a sale by sheriff's auction and divvy up the proceeds.