DUI Attorney in Walnut

Reviewed by Ron Chini, Esq. · CA State Bar No. 263308 · DUI defense attorney in Irvine, CA since 2009.
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How DUIs are policed in Walnut

Walnut has never run its own police force. Since incorporating on January 19, 1959, the city has contracted with the Los Angeles County Sheriff's Department, and deputies work out of the Walnut/Diamond Bar Sheriff's Station, 21695 E. Valley Blvd., Walnut, CA 91789, (909) 595-2264 — a joint station, led by Captain Steven Tousey, that patrols both Walnut and the separate City of Diamond Bar out of the same building, plus Rowland Heights and nearby unincorporated county pockets. That shared arrangement matters for a DUI defense: deputies responding to a stop on Grand Avenue in Walnut and one a mile away in Diamond Bar file through the identical station and chain of command, so a case built from this station's records looks much the same whichever of the two cities the stop happened in.

On the freeway side, State Route 60 (the Pomona Freeway) runs along Walnut's own southern edge, with the Fairway Drive and Brea Canyon Road interchanges both signed for Walnut specifically — and State Route 57 merges in just over the line in neighboring Diamond Bar at the 57/60 interchange. The California Highway Patrol's Baldwin Park Area office, 14039 Francisquito Avenue, Baldwin Park, lists SR-60 and SR-57 in its own coverage area, so a DUI stop made on the freeway itself — as opposed to on a Walnut surface street — more likely involves a CHP report rather than a Sheriff's one.

• Walnut has contracted with the LA County Sheriff's Department for police services continuously since its January 19, 1959 incorporation — there has never been a separate Walnut police department.
• The Walnut/Diamond Bar Station's jurisdiction spans two full cities (Walnut and Diamond Bar) plus Rowland Heights and nearby unincorporated areas — among the broader multi-city coverage areas of any LASD contract station in the eastern San Gabriel Valley.

Where a Walnut DUI case is likely heard

Walnut does not yet have an independently confirmed courthouse assignment on the county's own locator tools in the research behind this page. What is confirmed is that Walnut shares its entire policing arrangement — the same Walnut/Diamond Bar Sheriff's Station, the same deputies, the same contract — with the neighboring City of Diamond Bar, and Diamond Bar's DUI cases are routed to the Pomona Courthouse, 400 Civic Center Plaza, Pomona, CA 91766. Because a Walnut arrest and a Diamond Bar arrest are typically handled by the identical station and funneled into the same county court system, a Walnut DUI case is generally also heard at the Pomona Courthouse — but treat that as a reasoned inference from the shared station, not an independently verified fact specific to Walnut. Confirm the assigned courthouse and department from your own citation, or by calling the court clerk, before assuming anything.

One further wrinkle: some older sources describe a separate Pomona Courthouse North building at 350 W. Mission Blvd. historically used for certain misdemeanor filings, distinct from the main courthouse at 400 Civic Center Plaza. Whether that North building is still active isn't something this page can confirm — the court's own current courthouse-finder tool lists only the Civic Center Plaza location. Don't assume either address; the address to rely on with confidence is 400 Civic Center Plaza, Pomona, CA 91766, and your citation or the clerk's office will settle which building and department actually has your case.

Booking and getting a car back after a Walnut arrest

A DUI arrest anywhere in Walnut starts with intake at the Walnut/Diamond Bar Station, 21695 E. Valley Blvd. — but that building isn't where anyone is held for long. Standard county custody procedure routes adult arrestees from a contract station into the broader LASD jail system: men typically toward the Inmate Reception Center, Men's Central Jail, or Twin Towers downtown, and women toward the Century Regional Detention Facility in Lynwood. Exactly how quickly someone is released — on their own recognizance, by posting bail, or through a cite-and-release — depends on the specifics of the arrest, not a fixed rule. If a family member needs help figuring out where someone ended up after a Walnut stop, call our office.

Your vehicle is a separate issue from the arrest. After a routine DUI-related tow under Vehicle Code §22651(h), a licensed driver (or someone they authorize) can generally retrieve the car from the tow yard once the release paperwork and towing/storage fees are handled. The much stricter 30-day mandatory impound under §14602.6 is a different scenario entirely — it only applies when the driver was also unlicensed, suspended, or revoked at the time of the stop, not simply because the arrest involved a DUI. Ask Ron which rule applies to your specific stop during your free consultation.

From ranch land and a post office named "Lemon" to Mt. SAC's home city

Before it was Walnut, the area was grazing and ranch land tracing back to the Mexican-era Rancho Los Nogales land grant, planted over the decades with wheat, grapes, citrus, and walnut groves. The community's first post office, opened in 1895, was actually named "Lemon" after the citrus crop then common in the area; the name changed to Walnut in 1908, well before the city itself incorporated on January 19, 1959. That agricultural identity never fully disappeared — Walnut's own municipal code still carries an R-1 Rural overlay zone permitting residents on qualifying larger lots to keep horses and other domestic animals for private, non-commercial use, a holdover from the ranching era that distinguishes parts of Walnut from denser neighboring suburbs.

The city's best-known landmark is Mt. San Antonio College, 1100 N. Grand Ave., a 421-acre campus built on former Rancho La Puente land that served as an Army and then Navy hospital during World War II before the college opened in 1946. "Mt. SAC" is now one of the largest single-campus community colleges in California and hosts the Mt. SAC Relays, a nationally known track and field meet held at Hilmer Lodge Stadium since 1959 — the same year Walnut itself incorporated. As of the 2020 Census, Walnut's roughly 28,430 residents were about 67% Asian (non-Hispanic) and nearly 19% Hispanic or Latino, making it one of the more heavily Asian-American cities in the San Gabriel Valley. The city is also split between two school districts: most of Walnut falls under Walnut Valley Unified (shared with Diamond Bar), while the western edge of the city is served by Rowland Unified.

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Ron Chini, Esq.

DUI Defense Attorney · CA State Bar No. 263308

Ron defends DUI cases across Southern California from his Irvine office, in English and Farsi — and works directly with you, not a call center.

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