What Is the Legal Alcohol Limit in California?

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In California, it’s against the law to drive with a blood alcohol concentration (BAC) of 0.08% or higher if you’re 21 or older.

However, the state imposes additional requirements and penalties for certain drivers, such as underage drivers, ride-sharing drivers, and commercial drivers.

The consequences for violating California’s driving under the influence (DUI) laws can include potential jail time, license suspension, educational programs, and fines.

Given the potential life-altering nature of these charges, it is important to contact a California criminal defense attorney online or call 619-304-2058 to discuss how to defend against them. 

What Is Blood Alcohol Content? 

Blood alcohol content (BAC) is the percentage of alcohol in a person’s bloodstream. In California, BAC limits are used to determine a driver’s impairment.

The percentage is derived from the relative proportion of ethyl alcohol within the blood based on the number of grams of alcohol per milliliter of blood. For example, a BAC of 0.02% means 0.02 grams of alcohol or 100 milliliters of blood. 

What Is the Legal Alcohol Limit in California? 

The level limits of BAC in California vary depending on the type of driver and vehicle the driver is operating. The limits in BAC level in California include the following: 

  • Private Passenger Drivers 21 years and older. Private passenger drivers who are 21 years and older are DUI if their BAC is 0.08% or greater.
  • Drivers under 21. California has a zero-tolerance policy for drivers under 21 years old. Under this policy, individuals under the legal drinking age are considered DUI if they have a BAC of 0.01% or greater. 
  • Commercial Drivers. Drivers operating commercial vehicles, such as company trucks and buses, are considered DUI if their BAC is 0.04%.
  • Rideshare Drivers. Rideshare drivers, such as Uber, Lyft, and Blacklane drivers, are held to the same BAC limit as commercial drivers when transporting passengers.

Understanding the legal alcohol limit in California is essential for all drivers to ensure they meet the state’s strict BAC laws and avoid DUI charges. 

How Is BAC Measured and Tested?

California is an implied consent state, which means that if you drive in California and are lawfully arrested by an officer who has probable cause to suspect you of a DUI, you have provided your implied consent to a chemical test of your blood or breath to determine the alcohol content.

California’s implied consent laws apply to chemical breath and blood tests. They do not apply to preliminary alcohol screening tests. 

Breath Tests 

In California, if a law enforcement officer suspects you are driving under the influence, they may ask you to take a Preliminary Alcohol Screening (PAS) test.

Officers generally administer a PAS test using a handheld breathalyzer device. While refusing a PAS test does not carry direct penalties, drivers under 21 years old or those on DUI probation can face immediate license suspension. 

However, if you have been arrested for DUI, you will be given a choice of a breath or a blood test.

The law requires anyone lawfully arrested for DUI in California to take a breath or blood test, even if they previously took a PAS test. 

Blood Test

When administered correctly, blood tests are the most accurate BAC testing measure. In California, only certain professionals are authorized to draw blood for DUI testing.

Part of the sample is then sent to a lab for testing. If you believe you even may be close to the legal limit, you should always request a breath test instead of a blood test since the blood test is more accurate.

Urine Test

California rarely uses urine tests to measure BAC because they are less reliable than the other methods. 

In conjunction with other evidence, prosecutors use the results of a BAC test to prove either of the following:

  • The accused was over California’s legal limit and guilty of DUI per se; or
  • The accused was actually impaired and guilty of DUI. 

Choosing which type of chemical test to take is not a straightforward answer.

However, the most important thing to remember is that the test results will likely serve as the crux of the government’s case against you.

Accordingly, consulting with a criminal defense attorney as soon as possible is important. 

Unreliable BAC Results

Prosecutors often use BAC as crucial evidence in California DUI cases.

However, there are numerous factors and issues that can lead to inaccurate or unreliable BAC readings, both from breath tests and blood tests. Some factors include the following:

  • Machine errors,
  • Operator errors,
  • Blood sample contamination,
  • Chain of custody issues, and
  • Software glitches.

Addressing these potential inaccuracies and errors is crucial to preparing a viable defense. 

Factors That Impact Individual BAC 

It is commonly assumed that the amount of alcohol in the blood indicates the amount of alcohol consumed.

However, studies suggest several factors in an individual’s physiological profile, such as age, gender, body size, and drinking history, have been identified as predictors of how much alcohol a person must consume to reach a certain BAC. Additionally, the following factors may affect a person’s BAC:

  • Enzyme production,
  • Water consumption,
  • Sex assigned at birth and hormone levels,
  • Food, and 
  • Medications. 

While there are various charts and instruments that inform individuals of the factors that might impact their BAC, these devices are often confusing and inaccessible.

Reliance upon them can result in serious safety and legal consequences for individuals who fail to recognize the potential for an incorrect BAC estimation. 

Alcohol Content in Standard Drinks

Another factor individuals should be aware of is the discrepancy between standard drink sizes and how much a bar or restaurant may pour.

A “standard” drink is any beverage that contains about 0.6 fluid ounces of 14 grams of pure alcohol. However, bars often deviate from this amount. 

Are You Currently Facing California DUI Charges for an Elevated BAC?

If you’ve been arrested for a DUI in California, it’s important you understand all of the defenses that may be available to you.

At The Law Offices of Kerry L. Armstrong, APLC, we provide tenacious representation that is specifically catered to the specifics of your case.

Upon meeting with you for the first time, we will diligently listen to the facts of your case to discuss possible defenses.

Regardless of the facts, we are here to help improve your chances of resolving your case in a way that minimizes any impact on your future.

To learn more, and to schedule a free consultation today, give The Law Offices of Kerry L. Armstrong, APLC, a call today at 619-304-2058. You can also connect with us through a secure online contact form

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Kerry L. Armstrong


Attorney Kerry Armstrong opened up his law firm in June 2007. Mr. Armstrong attended Thomas Jefferson School of Law, San Diego, California, and received his B.S. from Middle Tennessee State University. Kerry L. Armstrong became certified by the State Bar of California’s Board of Legal Specialization for criminal law in August 2020, making him one of the few criminal defense attorneys with a criminal law legal specialization certificate in San Diego County.  Between 2014 – 2019, Mr. Armstrong was selected for inclusion in the California Super Lawyers list, an honor only awarded to 5% of the nation’s attorneys.