Legal Question in Real Estate Law in California

Yes, you can force a sale by filing an action for "partition" of the property. In the old days the court would take a large piece of jointly owned land and literally partition it. With modern land use and subdivision laws in place that is no longer possible, nor would it be possible with a single building, so the courts would then order a partition by sale, and divide the proceeds. You may be wrong,however, that no one would be interested in buying your half. If your partner would be cooperative in entering into a new partnership with a buyer in order to avoid having to buy you out, or being forced to sell, there might very well be investors interested in a deal. I may even know some. So if your partner would consider that option rather than face a partition action, let me know specifics about the property and I'll see if I can help.

Most co-owners don't want strangers as "partners." I think you'd have a fiduciary duty to notify your co-owner of your intention to sell your half, and this alone might kindle some interest in making a deal with you.

Also, just filing a partition suit will often result in an out-of-court settlement well before trial, or at least a renewed willingness to bargain on the part of a once recalcitrant co-owner.

If your co-ownership for 30+ years is legally a business partnership, which it could perhaps be even without an explicit partnership agreement or even a conscious intention to be partners, the laws governing its dissolution and winding up, including disposition of the property, are significantly different than with a garden-variety partition of property co-owned by non-partners. The way title is held is not necessarily dispositive. A lawyer familiar with partnership law as well as real-property (partition) law should assist you in deciding the legal nature of the co-ownership.