Being arrested can be one of the most overwhelming and frightening experiences in a person’s life. It can impact your career, finances, reputation, and relationships. At The Cespedes Law Firm, L.C., we understand how high the stakes are. That’s why we are committed to standing by you every step of the way, offering compassionate counsel and strong legal defense to individuals throughout California.
Our firm is led by a passionate and experienced attorney who, along with a skilled legal team, provides personalized, strategic representation aimed at securing the best possible outcomes. We are deeply familiar with every aspect of the California criminal justice system, and we use that knowledge to carefully guide you through the legal process while ensuring that you fully understand your rights and options.
Charged with a misdemeanor DUI in Diamond Bar? You’re facing license suspension, mandatory fines exceeding $1,800, DUI school, probation, possible jail time, and a criminal record that follows you to every job application, professional licensing board, and background check for years. Whether stopped on Diamond Bar Boulevard, Grand Avenue, the 57 Freeway, the 60 Freeway, or at a sobriety checkpoint anywhere in the City of Diamond Bar or surrounding communities, a DUI arrest is not a conviction—and you have the right to fight back. At Tu Defensor Criminalista, our bilingual criminal defense team has defended hundreds of DUI clients throughout Los Angeles County and the Pomona Valley area, protecting their licenses, their freedom, and their futures. Don’t plead guilty without understanding what you’re giving up. Call us now before you say a word to prosecutors.
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Stopped at a DUI checkpoint on Diamond Bar Boulevard or pulled over near Lemon Avenue and the 57 Freeway? Understanding exactly what the prosecution must prove—and where their case can fall apart—is the foundation of every successful DUI defense.
California Vehicle Code § 23152(a) makes it unlawful to drive a motor vehicle while under the influence of alcohol. California Vehicle Code § 23152(b) makes it separately unlawful to drive with a blood alcohol concentration (BAC) of 0.08% or higher. These are two separate charges that prosecutors routinely file together. Even if your BAC test result was below 0.08%, you can still be charged under § 23152(a) if an officer claims your driving was impaired. Conversely, even if you “felt fine,” a BAC of 0.08% or above triggers the per se DUI charge under § 23152(b).
For drivers under 21, California’s Zero Tolerance Law under Vehicle Code § 23136[1] makes it unlawful to drive with a BAC of 0.01% or higher—meaning even a single drink can result in a license suspension for a minor driver in Diamond Bar.
For commercial drivers operating vehicles on Diamond Bar’s commercial corridors or the 60 Freeway, Vehicle Code § 23152(d)[2] lowers the BAC threshold to 0.04%. A misdemeanor DUI conviction for a CDL holder is catastrophic.
What makes a first-offense misdemeanor DUI in California so damaging isn’t just the criminal case—it’s the parallel DMV administrative action. Within 10 days of your arrest, you must request a DMV Administrative Per Se (APS) hearing or your license is automatically suspended. This is a separate process from your criminal case, and missing that 10-day window closes the door on your ability to contest the suspension administratively. Our office handles both the DMV hearing and the criminal defense simultaneously.
¿Arrestado por DUI en Diamond Bar o en los alrededores de Walnut, Pomona, o Chino Hills? Usted enfrenta la suspensión de su licencia de manejar, multas superiores a $1,800, clases de DUI, libertad condicional, y posiblemente tiempo en la cárcel del Condado de Los Ángeles. En Tu Defensor Criminalista, nuestro equipo bilingüe de defensa criminal habla español con fluidez y entiende los retos únicos que enfrentan los conductores hispanos en el Valle de Pomona. Llámenos hoy mismo. Defendemos a clientes en Diamond Bar, Walnut, West Covina, Pomona, Chino Hills, y en todo el Condado de Los Ángeles.
The prosecution carries the burden of proof. They must prove beyond a reasonable doubt that you were (1) driving a motor vehicle and (2) under the influence of alcohol or had a BAC of 0.08% or higher. Our Diamond Bar DUI defense attorneys attack every link in the chain of evidence—starting from the moment an officer first observed your vehicle to the moment blood or breath results were recorded.
Every DUI case begins with a traffic stop or checkpoint encounter. Under the Fourth Amendment to the United States Constitution and Article I, Section 13 of the California Constitution[3], law enforcement officers must have reasonable suspicion of a traffic violation or criminal activity before pulling you over. If a Diamond Bar or Los Angeles County Sheriff’s Department deputy stopped your vehicle without lawful justification, any evidence obtained—including field sobriety tests, breathalyzer results, or statements you made—may be suppressed through a Motion to Suppress under Penal Code § 1538.5.
Common unlawful stop scenarios in Diamond Bar include:
The National Highway Traffic Safety Administration (NHTSA) recognizes only three standardized field sobriety tests (SFSTs): the Horizontal Gaze Nystagmus (HGN), the Walk-and-Turn (WAT), and the One-Leg Stand (OLS). According to NHTSA research[4], even under ideal conditions these tests have significant error rates. The HGN test—where an officer moves a pen in front of your eyes—can be failed due to medical conditions, fatigue, or certain prescription medications that have nothing to do with alcohol impairment. The WAT and OLS tests are performed on the side of a freeway or uneven ground, at night, often while a driver is nervous, elderly, or has a physical disability.
Our Diamond Bar DUI attorneys have extensive experience cross-examining officers on whether they were properly trained and certified in SFST administration, whether the tests were conducted on a level surface under adequate lighting, and whether any alternative explanations for poor performance were documented.
A roadside Preliminary Alcohol Screening (PAS) device result is generally not admissible as evidence of BAC at trial—it is used only to establish probable cause for arrest. The evidentiary breath test typically administered at the station or a mobile testing unit uses devices like the Draeger Alcotest or Intoxilyzer. These machines are not infallible. They must be regularly calibrated, maintained, and operated by trained personnel. California Code of Regulations Title 17 (17 CCR § 1220 et seq.[5]) establishes mandatory protocols for breath and blood testing in DUI cases. A violation of Title 17 regulations can render breathalyzer results inadmissible or unreliable.
Factors that can affect breath test accuracy include:
If your DUI case involves a blood draw, there are multiple additional points of attack. A blood sample must be properly collected, labeled, stored, and analyzed. Any break in the chain of custody creates reasonable doubt. Furthermore, the rising BAC defense is critical in many Diamond Bar DUI cases: alcohol absorbs into the bloodstream over a period of 30–90 minutes after your last drink. If you were still absorbing alcohol at the time of driving—meaning your BAC was lower when you were behind the wheel than when tested 45 minutes or an hour later at the station—the blood test result does not accurately reflect your BAC at the time of driving.
A first-offense misdemeanor DUI under Vehicle Code § 23152 in California carries severe consequences. The California DMV[6] and the California Penal Code combine to create a system of overlapping penalties that can impact every area of your life.
Criminal Penalties (First Offense):
DMV Administrative Penalties (First Offense):
Additional Consequences:
According to the Californ[8]i[8]a Office of Traffic Safety (OTS)[8], alcohol-involved traffic collisions remain one of the leading causes of traffic fatalities in California. In Los Angeles County—where Diamond Bar is located—DUI enforcement is aggressive and year-round. The City of Diamond Bar and surrounding communities including Walnut and Pomona are served by the Los Angeles County Sheriff’s Department (LASD) Walnut/Diamond Bar Station, which conducts regular DUI saturation patrols and checkpoint operations throughout the area.
Facing a second or third DUI in Diamond Bar? The stakes escalate dramatically with each prior conviction within a 10-year lookback period.
Second Offense DUI:
Third Offense DUI:
Under Vehicle Code § 23550[9], a third DUI conviction within 10 years can be charged as a felony, even if no injury occurred. If you have prior DUI convictions and are now facing a new DUI charge in Diamond Bar, contact our office immediately. The difference between a misdemeanor and a felony DUI charge is the difference between probation and state prison.
Charged with DUI causing injury near Diamond Bar? You’re facing wobbler charges under Vehicle Code § 23153[10]—meaning prosecutors can charge the offense as either a misdemeanor or a felony depending on the severity of injuries, your prior record, and other factors. A felony DUI with injury conviction can carry state prison sentences of 16 months, 2 years, or 3 years—and additional consecutive years for each injured victim under the California enhancement provisions. Restitution to victims can total hundreds of thousands of dollars.
Even if injuries were minor, prosecutors in Los Angeles County aggressively pursue felony charges in DUI accident cases. Our Diamond Bar DUI defense attorneys challenge accident reconstruction reports, medical causation claims, and the prosecution’s evidence linking impairment to the cause of the collision.
Diamond Bar is served by the Los Angeles County Sheriff’s Department Walnut/Diamond Bar Station, located at 21695 Valley Boulevard, Walnut, CA 91789. LASD conducts regular DUI enforcement operations throughout Diamond Bar, including on Diamond Bar Boulevard, Grand Avenue, Golden Springs Drive, Brea Canyon Road, and along the 57 and 60 Freeway corridors.
California law permits sobriety checkpoints under Ingersoll v. Palmer (1987)[11], but checkpoints must meet strict constitutional requirements: they must be publicly announced in advance, operated under neutral, mathematical criteria for stopping vehicles, and supervised by supervisory law enforcement personnel. Failure to comply with these requirements can result in the suppression of all evidence obtained at the checkpoint.
The California Office of Traffic Safety[8] provides grant funding to local agencies including LASD for DUI checkpoint operations throughout Los Angeles County. These checkpoints are often conducted during holiday weekends, summer months, and special events. If you were arrested at a Diamond Bar area DUI checkpoint, our attorneys will obtain the operational plan and evaluate whether constitutional requirements were met.
According to Los Angeles County’s traffic safety data[12], the San Gabriel Valley including Diamond Bar experiences significant DUI enforcement activity. The City of Diamond Bar is located in the 57th and 60th Assembly Districts and is subject to California-wide DUI laws enforced by LASD with backup from the California Highway Patrol (CHP) on state freeways.
Understanding the court process helps you make informed decisions about your defense.
Convicted of a misdemeanor DUI in Diamond Bar? After completing probation successfully, you may be eligible for an expungement under Penal Code § 1203.4[13]. An expungement allows the court to withdraw your guilty plea or verdict, enter a not guilty plea, and dismiss the case. While an expunged DUI conviction still appears on your DMV driving record and must be disclosed in certain professional license applications, it is generally not required to be disclosed on private employment applications and significantly reduces the impact of a DUI conviction on your background check.
Our Diamond Bar DUI attorneys guide clients through the expungement process from start to finish. If you are currently on probation and seeking an early termination of probation as a prerequisite to expungement, we handle that petition as well.
Diamond Bar is a city of approximately 55,000 residents in Los Angeles County, incorporated in 1989. It sits at the junction of the 57 and 60 Freeways—one of the busiest freeway interchanges in the Eastern San Gabriel Valley. The city is known for its hillside residential neighborhoods, Diamond Bar Center, and South Pointe Middle School. Its location at the junction of two major freeways makes it a significant corridor for CHP enforcement as well as LASD patrols.
According to the California Office of Traffic Safety Annual Report[8], Los Angeles County consistently records among the highest numbers of DUI arrests, DUI fatalities, and DUI injuries of any county in California. In recent years, DUI enforcement has expanded beyond alcohol to include marijuana DUI under Vehicle Code § 23152(f) and drug DUI under § 23152(e), reflecting California’s legalization of recreational cannabis under Proposition 64 (California Department of Cannabis Control[14]).
The National Highway Traffic Safety Administration (NHTSA)[4] reports that drunk driving fatalities account for approximately 28% of all traffic fatalities in the United States. In California, the Statewide Integrated Traffic Records System (SWITRS)[15], maintained by the California Highway Patrol, tracks all traffic collision data including DUI-involved collisions. This data drives aggressive enforcement policies throughout Los Angeles County communities including Diamond Bar.
California legalized recreational cannabis under Proposition 64, but driving under the influence of cannabis remains illegal under Vehicle Code § 23152(f)[2]. Unlike alcohol, there is no established per se BAC limit for THC. Instead, prosecutors rely on Drug Recognition Expert (DRE) evaluations, blood THC levels, and circumstantial evidence of impaired driving to prove marijuana DUI.
The science of marijuana DUI prosecution is far less settled than alcohol DUI. THC can remain in the bloodstream for days or weeks after last use in chronic users—meaning a blood test showing THC does not prove impairment at the time of driving. Our Diamond Bar DUI defense attorneys challenge DRE evaluations, blood draw procedures, and the prosecution’s scientific evidence in marijuana and drug DUI cases.
Charged with DUI as a minor in Diamond Bar? Under Vehicle Code § 23140[16], a driver under 21 with a BAC between 0.05% and 0.07% can be charged with an infraction-level offense. Under Zero Tolerance Vehicle Code § 23136, any measurable BAC (0.01% or higher) triggers a one-year license suspension. A DUI conviction before age 21 can jeopardize college enrollment, scholarships, professional licensing, and military service. Our attorneys fight aggressively for young clients in Diamond Bar and throughout Los Angeles County.
Commercial drivers operating on the 60 Freeway, the 57 Freeway, or Diamond Bar’s surface streets face a 0.04% BAC standard under Vehicle Code § 23152(d). A DUI conviction for a CDL holder results in a mandatory one-year CDL disqualification for a first offense—and a lifetime CDL disqualification for a second offense. This is a career-ending consequence for professional truck drivers, bus drivers, and other commercial operators. Our Diamond Bar DUI attorneys fight CDL-related DUI charges with the same intensity as felony cases.
You are required to provide your driver’s license, registration, and proof of insurance. Beyond that, you have the right to remain silent under the Fifth Amendment. You are not required to answer questions about where you’ve been, how much you’ve had to drink, or where you’re going. Politely decline field sobriety tests—they are voluntary for drivers over 21 in most circumstances. After a lawful arrest, you are required to submit to a chemical test (breath or blood) under California’s implied consent law, or face an automatic license suspension and an “Implied Consent” finding that can be used against you.
You can refuse a roadside PAS (preliminary breath test) if you are over 21 and not on DUI probation. However, after a lawful DUI arrest, you are required under California’s implied consent law (Vehicle Code § 23612[17]) to submit to a chemical test—either breath or blood. Refusal results in a mandatory one-year license suspension (first offense) or longer for prior offenses, regardless of whether you are convicted of DUI.
A DUI conviction stays on your California DMV driving record for 10 years. It stays on your criminal record indefinitely unless expunged under Penal Code § 1203.4. After successful completion of probation, you may petition for expungement, which limits the impact on private employment background checks.
Almost certainly without legal action. You have 10 days from arrest to request a DMV APS hearing to contest the administrative suspension. If you do not request the hearing, your license is automatically suspended 30 days after arrest. Our attorneys request the hearing on your behalf and fight to preserve your driving privileges.
A “wet reckless” is a reduction of a DUI charge to reckless driving with an alcohol notation under Vehicle Code § 23103/23103.5. It carries fewer penalties than a DUI—generally no mandatory license suspension, a shorter probation period, lower fines, and the possibility of avoiding the DUI label on your record. Whether a wet reckless is available depends on the strength of the prosecution’s evidence, your prior record, and the specific facts of your case. Our attorneys negotiate aggressively for the best possible outcome.
A second DUI arrest while on DUI probation is extremely serious. In addition to new DUI charges, the prosecution will file a probation violation petition. You face the penalties for the new DUI plus revocation of probation on the prior offense—meaning the suspended jail sentence on the prior conviction can be imposed. Contact our office immediately.
A DUI conviction can have serious immigration consequences for non-citizens, including impacts on visa renewals, green card applications, adjustment of status, and naturalization. Depending on your specific immigration status and the nature of the DUI charge, the consequences range from serious to devastating. Our bilingual team understands the intersection of criminal and immigration law and will advise you on potential immigration consequences before any plea is entered.
Attorney fees vary based on the complexity of your case, whether it is a first offense or repeat offense, whether it involves injury or enhanced charges, and whether the case goes to trial. We offer free initial consultations and will give you a clear fee structure upfront with no hidden costs. Call us or visit our website at tudefensorcriminalista.com to schedule your consultation.
Yes. After completing probation successfully, you may petition the court for expungement under Penal Code § 1203.4. An expunged DUI is generally not required to be disclosed on private employer job applications, though it remains on your DMV record for 10 years and must be disclosed in certain professional licensing contexts. Our office handles DUI expungement petitions throughout Los Angeles County.
DUI cases arising in Diamond Bar are heard at the Pomona Courthouse, located at 400 Civic Center Plaza, Pomona, CA 91766. This courthouse serves the Pomona Judicial District, which includes Diamond Bar, Walnut, Pomona, and several surrounding communities.
Remember:
Attorney Armando Josué Cespedes is rated 5.0 on Avvo, with 34 five-star reviews from clients praising his dedication, professionalism, and results. Many note how his trial skills and attention to detail led to reduced charges or outright dismissals.
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