Contra Costa County, CA Public Conduct: Loud Party Ordinance (2026)
Key Facts
- Threshold
- 3+ people under 21 present
- Alcohol requirement
- Possessed or consumed by a minor
- Penalty
- Misdemeanor: up to 6 mo. jail, $1,000 fine
- Who is liable
- Anyone hosting or controlling the property
- Exception
- Alcohol use protected by Cal. Const. art. I, §4
- Applies to
- Unincorporated Contra Costa County only
Summary
Hosting or allowing a gathering of three or more people under 21 where alcohol is present or being consumed on property you control is a misdemeanor in unincorporated Contra Costa County. The Social Host Ordinance holds property owners, renters, and anyone controlling the premises liable, punishable by up to six months in county jail, a $1,000 fine, or both.
(a)No person shall suffer, permit, allow, or host a gathering at the person's place of residence or other private property under the person's control where three or more persons under the age of twenty-one are present and where alcoholic beverages are in the possession of, or are being consumed by, any person under the age of twenty-one.(b)A violation of this chapter is a misdemeanor, punishable by imprisonment in the county jail not exceeding six months, or by fine not exceeding one thousand dollars, or by both.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Ordinance Code: Supplement 103).
Full Breakdown
Adopted by Ordinance No. 2008-25 and amended by Ordinance No. 008(a) makes it unlawful for any person to 'suffer, permit, allow, or host a gathering' at a place of residence or other private property the person controls where three or more people under 21 are present and alcoholic beverages are in the possession of, or being consumed by, any person under 21. 004 explain the rationale: underage drinking gatherings are hard to control unless the sheriff's office can hold hosts, not just the minors themselves, responsible for the resulting noise, vandalism, fights and other alcohol-related problems.
006(b) to include any private property a person owns, rents or leases, so a tenant hosting a party on rented property is equally liable, not just homeowners. 008(c) carves out a narrow exception for gatherings involving alcohol protected under Article 1, Section 4 of the California Constitution. 008(a).
Violations & Fines
A violation of the Social Host Ordinance is charged as a misdemeanor under Section 54-3.008(b), punishable by up to six months in county jail, a fine of up to $1,000, or both. The sheriff's office may cite the host, property owner, or whoever controls the premises where the underage gathering took place, regardless of who bought or brought the alcohol.
Frequently Asked Questions
What counts as an illegal gathering under the county's social host law?
What is the penalty for violating the Contra Costa Social Host Ordinance?
Can a landlord be cited if a tenant's party violates the ordinance?
Sources & Official References
Other rules in Contra Costa County
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