Short answer

If a co‑owner heir lives in inherited real property and refuses to move or to agree to a sale, the usual legal remedy in California is a partition action. A court can divide the property physically if feasible or order a forced sale and divide the proceeds among the owners. If a co‑owner has no legal right to exclusive possession, the court can also address possession and compensation for use. In some circumstances an unlawful detainer (eviction) may apply, but eviction is typically not the first or correct remedy when co‑owners dispute ownership—partition is.

Detailed answer — how California law typically handles this

1. Confirm ownership and possession rights

First, determine how title to the property was transferred after the decedent died. If title passed through probate or was otherwise vested in multiple heirs, those heirs are co‑owners (cotenants). As co‑owners, each person generally has an equal right to possession of the entire property, regardless of percentage ownership. That means one co‑owner cannot simply exclude another co‑owner unless the court grants relief.

2. Partition actions — the primary remedy

When co‑owners cannot agree about possession or sale, any co‑owner can file a partition action under California law. The statute authorizing partition suits provides that a co‑owner may bring an action to partition real property held by two or more persons. See California Code of Civil Procedure § 872.010 for the basic authority to bring a partition action: CCP § 872.010.

In a partition action the court has two main options:

• Partition in kind: physically divide the land so each owner receives a portion (possible when the property can be divided without substantial prejudice to owners).
• Partition by sale: order a judicial sale and split the sale proceeds according to each owner’s share (used when physical division is impractical or would be unfair).

The court will consider practical factors (shape, size, improvements, and whether dividing would materially reduce value) when deciding between division in kind or sale. If the court orders a sale, the proceeds are distributed to the owners according to their ownership shares after costs, liens, and any court‑awarded credits or charges.

3. Possession, rent, and accounting

If a co‑owner occupies the property and excludes others or uses the property to the exclusion of co‑owners, the other co‑owners can ask the court for an accounting of rents and profits. The court can credit or charge owners for use and occupation during the dispute. Courts commonly offset occupancy value against the occupant’s share or require payment to other owners.

4. Eviction / unlawful detainer — when it applies

Eviction law (unlawful detainer) in California addresses wrongful possession under landlord‑tenant or similar relationships. If the person occupying the property is not a co‑owner and lacks consent, a property owner may pursue an unlawful detainer action under California Code of Civil Procedure § 1161 and related provisions: CCP § 1161. But if the occupant is a cotenant (an heir who holds title with you), unlawful detainer is often inappropriate because cotenants generally have a legal right to possession; partition is the correct route.

5. Practical outcomes and court powers

Possible court outcomes include:

• Ordering a physical division of property (rare for residences where division would be impractical).
• Ordering a sale and dividing proceeds among the heirs according to shares.
• Awarding credits for improvements or charging an occupant for use and occupation.
• Resolving lien or mortgage issues as part of the distribution.
• Assigning responsibility for costs, attorney fees, and sale expenses (the court has discretion to allocate costs).

6. Alternatives to immediate litigation

Before filing suit you can explore negotiation, mediation, or a buy‑out: an heir can pay other owners for their shares; co‑owners can sign a written agreement setting possession and sale terms; or the family can agree to sell on the open market. These options are often faster and cheaper than a court action.

7. Timeline and costs

Partition actions can take months to years depending on complexity, title issues, liens, and court calendar. Expect court costs, appraisal fees, possible broker commissions on sale, and attorney fees if you hire counsel. A negotiated settlement usually costs less and resolves faster.

8. When to contact an attorney

Talk to a California attorney if any of these are present: unclear title after probate, mortgages or liens, significant disagreement over value or division, a co‑owner who refuses to allow access, or risk of waste or damage to the property. A lawyer can explain options, file a partition action, pursue equitable relief, or prepare a buy‑out agreement.

Helpful hints

• Confirm title: get a copy of the recorded deed or probate distribution docs to know who has legal ownership.
• Check for mortgages, liens, or tax obligations before negotiating or buying out an heir.
• Get a current appraisal to establish fair market value before discussing buyouts or sale.
• Document conversations and offers in writing. Written agreements avoid misunderstandings later.
• Consider mediation: a neutral mediator can help heirs reach a sale or buyout agreement faster and cheaper than a lawsuit.
• If you suspect the occupying heir is damaging or wasting the property, preserve evidence (photos, invoices) and speak with counsel quickly—courts can stop waste.
• Understand costs: partition suits involve court filing fees, appraisals, and possibly broker commissions and attorney fees; factor those into any buyout offer.
• If you are not sure whether the occupant is a co‑owner or a tenant, review title documents and any written agreements—this determines whether partition or unlawful detainer is the right remedy.