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Earlier editions: 2026-09

Title 3 — PUBLIC SAFETY, MORALS AND WELFARE

San Mateo County Municipal Code Ch. 3.05 Prohibition of Loud or Unruly Gatherings Where Any Alcohol, Alcoholic…

San Mateo County Municipal Code · 2026-10 edition · updated 2026-10-04 · San Mateo County

Cite as: San Mateo County Municipal Code Chapter 3.05 · Text as of 2026-10-04

3.05.010 - Application of Chapter.

The provisions of this chapter shall apply within the unincorporated area of San Mateo County.

(Ord. No. 04810, § 1, 2-26-2019)

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3.05.020 - Definitions.

For the purposes of this chapter, the following words and phrases shall be construed as follows:

(a) "Alcohol" and "Alcoholic Beverage" include any form of ethyl alcohol, from whatever source or by whatever process produced, spirits, liquor, wine, beer, and every liquid or solid containing such, and which contains one-half of one percent or more alcohol by volume and which is fit for beverage purposes either alone or when diluted, mixed, or combined with other substances.

(b) "Cannabis" means "cannabis", "cannabis product" and/or "cannabis concentrate", as defined in Chapter 5.148 of this ordinance code. For the purposes of this chapter, the term "cannabis" does not include medical cannabis for which the person in possession has a valid recommendation for medical cannabis from a licensed medical care provider or a State of California medical cannabis I.D. card.

(c) "Controlled Substance" means a drug or substance whose possession and use are regulated under the California Controlled Substances Act (California Health and Safety Code Section 11000 et seq.). Such term does not include any drug or substance for which the individual found to have consumed or possessed such substance has a valid prescription issued by a licensed medical practitioner authorized to issue such a prescription.

(d) "Costs for Public Safety Response Services" means the costs associated with responses by law enforcement or fire agencies to a gathering held in violation of this ordinance, including but not limited to:

(1) The portion of the cost of salaries of the police officers and/or fire agency personnel, at the salary then in effect for each classification of each individual officer, for the actual amount of time spent responding to or remaining at the property where the disturbance was created, beginning when police officer or fire department personnel leaves a location to go to the scene of the event and ending when responding personnel are available for other duties, or, if their shifts are ended, when they are finished with those duties related to the event which they are required to complete before going off duty, or a minimum of one hour of time, whichever is greater. Such actual costs shall include wages and fringe benefits for the responding personnel and the sergeant or other superior directing them, including overtime if applicable; and

(2) The cost of repairing, or replacing if necessary, any County or fire agency equipment or property damaged as a result of the response by law enforcement or fire agency to the gathering.

(e) "Loud or Unruly Gathering" means a party or gathering of four (4) or more persons at any public or private premises, including a party bus or limousine, upon which loud or unruly conduct occurs. Such loud or unruly conduct constitutes a public nuisance and includes the following:

(1) Excessive noise which violates any applicable ordinance;

(2) Obstruction of public streets and/or the presence of unruly crowds that have spilled into public streets;

(3) Public drunkenness or unlawful public consumption of alcohol, alcoholic beverages, cannabis, and/or controlled substances;

(4) Assaults, batteries, fights, domestic violence or other disturbances of the peace;

(5) Vandalism;

(6) Litter; or

(7) Any other conduct which constitutes a threat to the public health, safety, or quiet enjoyment of residential property or the general welfare.

(f) "Minor" means any person less than twenty-one (21) years of age.

(g) "Responsible Person" or "Social Host" means and includes, but is not limited to:

(1) A person who owns, rents, leases, or otherwise has control of the premises where the gathering occurs; and/or

(2) A person who organized the event.

(Ord. No. 04810, § 1, 2-26-2019)

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3.05.030 - Obligations of Social Host.

(a) No person shall act as a Social Host, as defined in Section 3.05.020 of this chapter, of a Loud or Unruly Gathering where a Minor has possessed, consumed, or has been served any Alcohol, Alcoholic Beverage, Cannabis, and/or Controlled Substances.

(b) It is the duty of any Responsible Person who knowingly hosts, permits, or allows a gathering at any public or private premises to take all reasonable steps to prevent the possession and/or consumption of any Alcohol, Alcoholic Beverage, Cannabis and/or Controlled Substance by any Minor, as well as the service of these items to any Minor.

(c) As used in this section, reasonable steps shall mean and include, but shall not be limited to:

(1) Controlling access to Alcohol, Alcoholic Beverages, Cannabis and/or Controlled Substances;

(2) Verifying the age of persons at the gathering by inspecting government-issued driver's licenses or identification cards; and

(3) Supervising the activities of Minors at the gathering.

(Ord. No. 04810, § 1, 2-26-2019)

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3.05.040 - Public Nuisance.

Any gathering in violation of this chapter is a public nuisance and an immediate danger to public health and safety. A violation is subject to any and all applicable civil, administrative, and criminal remedies and penalties according to the provisions and procedures contained in this ordinance code and state law including, but not limited to, an abatement action. All remedies provided herein shall be cumulative and not exclusive.

(Ord. No. 04810, § 1, 2-26-2019)

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3.05.050 - Enforcement.

(a) The San Mateo County Sheriff or designee, may enforce this chapter.

(b) A violation of this chapter is punishable by administrative fines as set forth in Chapter 1.40.

(c) In addition, a third or subsequent violation will result in liability on the part of the social host(s) for Costs for Public Safety Response Services as defined in Section 3.05.020 of this chapter. All responsible parties will be held jointly and severally liable for these costs.

(d) All fines and Costs for Public Safety Response Services shall be paid to the County within fourteen (14) days from the date of the citation or the notice of costs to be reimbursed under this ordinance.

(e) This chapter shall not be interpreted to limit the applicable civil or administrative remedies available under law. All available enforcement procedures and remedies remain applicable including, but not limited to, administrative fines set forth in Chapter 1.40 of this ordinance code or other applicable law.

(Ord. No. 04810, § 1, 2-26-2019)

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3.05.060 - Emergency Medical Assistance Exception.

No citation may be issued or any other enforcement action taken for violation of this chapter if law enforcement is dispatched to the gathering because a Social Host or other participant at the gathering sought medical assistance on behalf of any person present. This section should be interpreted consistent with its purpose—to encourage social hosts and participants of gatherings to seek medical assistance whenever they believe it is needed, without fear of the consequences of violating the Ordinance.

(Ord. No. 04810, § 1, 2-26-2019)

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3.05.070 - No Conflict with Federal or State Law.

Nothing in this chapter shall be interpreted or applied so as to create any requirement, power, or duty that is preempted by federal or state law.

(Ord. No. 04810, § 1, 2-26-2019)

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3.05.080 - Severability.

If any provision, section, subsection, sentence, clause, phrase, or word of this Chapter 3.05, or any application thereof to any person or circumstance, is held to be invalid or unconstitutional by a court of competent jurisdiction, such decision shall not affect the validity of the remaining portions or applications of the chapter. The Board of Supervisors hereby declares that it would have passed this chapter, and each provision, section, subsection, sentence, clause, phrase, and word not declared invalid or unconstitutional without regard to whether any portion of this chapter or application thereof would be subsequently declared invalid or unconstitutional.

(Ord. No. 04810, § 1, 2-26-2019)

Exceptions & meaning →

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