Detailed Answer — step‑by‑step under California law

Before an agent lists and markets real estate in California, you must make sure the person(s) who legally control the property agree in writing. The exact steps depend on how title is held (individual owner, married couple, co‑owners, trust, estate, power of attorney, guardianship, HOA restrictions). Follow these steps to minimize risk and make the listing valid and enforceable:

1. Identify the legal decision‑makers.

   Start by checking the deed, title report, trust documents, will, or court papers to learn who can approve a sale or a listing. Common situations:

   • Joint tenants or tenants in common: each named owner on title usually must sign the listing and the eventual deed transfer.
   • Married owners and community property: both spouses typically must join in conveying community property (see California Family Code § 760).
   • Trust property: the trustee (per the trust instrument) controls trust assets; beneficiaries generally cannot unilaterally veto a trustee’s decision unless the trust limits the trustee’s authority.
   • Probate estate: the personal representative (executor/administrator) or the probate court may need to approve marketing and sale.
   • Power of Attorney (POA): an agent with valid real‑property authority may sign if the POA grants that power and is properly executed.
2. Pull an official title report and read recorded documents.

   Order a preliminary title report or examine the deed and any recorded encumbrances. Check for mortgages, liens, easements, judgments, or recorded powers of attorney or trust instruments that affect who must sign or whether a sale requires another party’s consent.

3. Confirm whether unanimous consent is legally required.

   If multiple owners appear on title, you generally need all owners to authorize listing the entire property. If one co‑owner won’t agree, the disagreeing owner can still force a partition action in court to sell or divide the property (see California Code of Civil Procedure, partition statutes). A court‑ordered sale or partition is a formal remedy when owners cannot agree.

4. Get written, signed authority from whoever controls the property.

   Use a properly completed listing agreement signed by all required owners or their authorized representatives. Written signatures are the clearest proof of consent. If an owner signs by POA, keep a copy of the POA document and verify it grants real‑property authority.

5. Verify identity and authority on recorded documents.

   Ask to see government ID and, if someone signs as a trustee, provide the trust name, the trustee’s name, and a copy of the trust (or the portion proving trustee authority). For POAs, confirm the POA is current, notarized/executed correctly, and permits the agent to sell or list real estate. If the property is community property, confirm both spouses sign as needed (Family Code § 760).

6. Follow special rules for probate, conservatorships, and trusts.

   When the property is in probate or a conservatorship, the representative may need court authorization before marketing, or the sale may require court confirmation—procedures differ from private sales. For trust property, confirm the trust gives the trustee power to sell and whether the trustee must notify beneficiaries or obtain court relief.

7. Document and retain copies of all approvals.

   Keep copies of the listing agreement, signatures, POA, trust excerpts, court orders, title report, and any written consents. These records prevent disputes later and show the broker complied with duty of care and agency rules.

8. If someone refuses to agree, attempt negotiation or use formal remedies.

   Options include mediation, a buyout of the objecting owner’s interest, or a partition action (court‑ordered sale or division). A partition action is a remedy of last resort when co‑owners cannot reach a deal.

9. Comply with seller disclosure and licensing rules before marketing.

   Even with all approvals, the seller must comply with California disclosure requirements (e.g., Transfer Disclosure Statement) and brokers must follow Department of Real Estate (DRE) rules. Ensure the listing agent is properly licensed (see California DRE: https://www.dre.ca.gov/).

10. When in doubt, get a short legal review.

    If title or authority is unclear, consider a brief attorney review or written opinion before spending on marketing. A lawyer can prepare consent forms, short affidavits, or seek court guidance when required.

Key California statutes and resources to review:

• California Family Code § 760 (definition of community property): leginfo.legislature.ca.gov – Fam. Code § 760
• California Code of Civil Procedure — partition actions (see relevant sections in the CCP): leginfo.legislature.ca.gov – CCP (partition)
• California Department of Real Estate (licensing and broker duties): dre.ca.gov

Following these steps will reduce the risk of a contested sale and ensure the broker can market the property with confidence that the people with legal authority gave informed, written consent.

Helpful Hints

• Always get written signatures on the listing agreement from every owner named on title or their properly authorized representative.
• If an owner signs by POA, record a copy of the POA and confirm it specifically authorizes real estate transactions.
• If title shows “joint tenants” or “tenants in common,” confirm whether each owner intends to sell the entire property or only an owner’s share.
• For married couples, err on the side of getting both spouses to sign—even if title lists only one spouse—when community property may be involved (Family Code § 760).
• If beneficiaries or heirs contest a trustee’s or executor’s decision, consider a short delay to mediate rather than immediately spending on marketing or accepting offers.
• Obtain an updated preliminary title report early. Title problems can block marketing and escrow later.
• Use neutral, signed consent forms tailored to your situation (co‑owner consent, trustee certification, executor’s authority, POA certification) so brokers and buyers see a clean paper trail.
• When marketing estate or trust property, disclose the status (trust, probate) to agents and buyers; it may affect timing and buyer financing.
• Consult a real estate attorney if any court approval might be required—e.g., probate court confirmation—or if one owner refuses to cooperate.