The short answer
To have police act on trespass at your California property without calling you every time, file a 602 letter — a trespass arrest authorization under Penal Code section 602(o) — with your local police or sheriff. It appoints law enforcement as your agent, runs for up to 12 months (longer, up to three years, for property that is permanently closed and posted as such), and generally requires posted “No Trespassing” signage to be enforceable. Enforcement is usually by citation rather than arrest absent other criminal conduct. Critically, a 602 letter does not work against someone who has established residency — that is an unlawful detainer matter, not a trespass one.
There are two completely different problems hiding behind “someone is on my property and I want them gone,” and they have different remedies, different timelines and different costs. Getting the wrong one is how an owner loses six weeks.
| Trespasser | Person with a possessory interest | |
|---|---|---|
| Who this is | No claim of right to be there. Someone cutting through a yard, camping in a lot, loitering in a lobby, entering a construction site. | A holdover tenant, an unauthorised occupant who has established residency, someone claiming a verbal tenancy, a former guest who will not leave. |
| Remedy | Trespass law. Police can cite or arrest, especially with a 602 letter on file. | Unlawful detainer — a civil eviction action through the courts. |
| How fast | Same day, on a police response. | Weeks, sometimes months, depending on the court. |
| What police typically say | They will act, particularly with a filed authorization and posted signage. | "This is a civil matter." And they are usually right. |
| Where owners go wrong | Not filing the letter, or filing it and never posting the signs. | Trying to use trespass law or self-help to shortcut an eviction. Both make things worse. |
The line moves faster than owners expect
What a 602 letter is, and what it is for
Ordinarily, police responding to a trespass call need someone with authority over the property to be present, or reachable, to say that the person is not permitted there. At 3am on a Sunday that is a problem. A trespass arrest authorization solves it: by filing under Penal Code section 602(o), you appoint law enforcement as your agent in advance, so an officer can act on a person present without lawful business without tracking you down first.
The procedure varies by agency, but the common requirements are consistent:
- A signed letterfrom the owner or an authorised agent, on the agency's form where one exists. Many departments require it notarised.
- Posted signage.Typically “No Trespassing — Loitering Forbidden by Law” with the code section, at entrances and at intervals around the property. This is what establishes notice, and a letter without signs is frequently unenforceable.
- A defined term. Section 602(o) caps the authorization at 12 months, so expect to renew annually. Property that is permanently closed and posted as such can be covered for longer — up to three years.
- A named contact. Someone the agency can reach about the property.
602 letters at a glance
- Statute
- California Penal Code §602(o)
- Also called
- Letter of Agency, trespass arrest authorization
- Filed with
- Your local police department or sheriff station
- Standard term
- Up to 12 months; renew annually
- Permanently closed property
- Can run up to three years where posted as such
- Signage
- Required in practice — confirm wording and placement locally
- Typical enforcement
- Citation rather than arrest, absent other criminal conduct
- Does not cover
- Tenants, holdovers, or anyone with established occupancy
What a security officer can and cannot do
This is worth being precise about, because the expectation gap causes real problems on site. A licensed California security officer is a private person with a uniform, a BSIS guard card and a defined scope. They are not police.
| An officer can | An officer cannot |
|---|---|
| Ask a person to leave and explain that they are trespassing | Use force to remove someone as a matter of routine |
| Deny entry and control access at a gate or door | Detain someone indefinitely |
| Document the encounter — time, description, what was said | Search a person or their belongings |
| Photograph and log repeat individuals for the property record | Issue citations |
| Call law enforcement and brief them on arrival | Exercise police powers of any kind |
| Provide a written statement supporting a later prosecution | Give legal advice about your remedies |
California does permit a private person arrest under Penal Code section 837 in narrow circumstances. In practice a responsible provider trains officers away from it: the legal risk falls on the officer and, through them, on the property owner, and the situations where it is genuinely the right call are rare. What actually reduces trespass on a property is consistent presence, a person who knows the regulars by sight, and a documented record that makes the next police contact straightforward. Our officers log encounters with timestamped, GPS-verified checkpoints, which is what turns “this keeps happening” into a record an agency can act on.
A practical sequence
- Establish which problem you have. Trespasser, or someone with apparent occupancy? Everything downstream depends on this answer, and getting it wrong costs weeks.
- If it is trespass, file the 602 letter now. Call your local police or sheriff, ask for their trespass arrest authorization procedure, and file it. Do it before you need it — filing during an incident helps nobody.
- Post compliant signage and photograph it. Entrances and intervals. Keep dated photographs, because signage that was up in March and gone in June is a defence argument later.
- Document every incident. Date, time, description, what was done, whether police attended, any citation number. A pattern is what escalates a response.
- Add patrol if the pattern is persistent. Scheduled vehicle patrol at irregular times, with verifiable checkpoints, deters far more effectively than a fixed post — the pattern cannot be learned. On vacant property this is usually the cost-effective answer.
- If occupancy has been established, stop and call an attorney.Do not change locks, remove belongings, cut utilities, or have anyone “escort them out.” California treats self-help eviction seriously and it converts your problem into their claim. Unlawful detainer is slower, and it is the route that works.
Never let anyone talk you into self-help
Recurring trespass on a property?
Scheduled patrol with verifiable checkpoints is usually the cost-effective answer for vacant and low-traffic sites — a standing officer rarely justifies the cost. Tell us the address and the pattern and we will quote the coverage that actually fits.
For vacant buildings and land specifically, our vehicle patrol page covers how the routes and checkpoint verification work, and the cost guide shows what patrol coverage runs against a standing post.
This is general information, not legal advice. Filing procedure, signage wording and enforcement practice for trespass authorizations vary between California agencies, and the trespasser/occupant distinction turns on specific facts. Confirm the procedure with the agency that will hold your letter, and speak to a California attorney before acting against anyone who may have a possessory interest in the property.
