What is the Legal BAC in California?

by Ambrosio Rodriguez | Mar 02, 2018 | DUI

In California, it’s against the law to drive if you’re under the influence of alcohol. Alcohol affects everyone differently, so how can police determine if you’re intoxicated in violation of the law? The state has drawn an arbitrary line which holds all drivers to the same standard. This standard relies on what is known as your blood alcohol concentration, or BAC. When your BAC exceeds the legal limit you can be charged with a DUI.

Blood Alcohol Concentration

Blood alcohol concentration is the measurement of the amount of alcohol in your blood. This measurement can be calculated in one of two ways:

  1. Grams of alcohol per 100 ML of blood, or
  2. Grams of alcohol per 210 liters of breath.

The calculation is expressed in the form of a percentage. The more alcohol you’ve consumed, the higher your BAC reading will be. Multiple studies have shown that a person’s ability to drive safely becomes compromised when their blood alcohol concentration reaches .08 percent.

What Affects a Driver’s Blood Alcohol Concentration?

Alcohol affects everyone differently. We all have unique metabolisms and environmental factors can play a significant role. This means that if two people consume an identical amount of alcohol, it does not necessarily mean that their blood alcohol concentrations will be the same. Factors that can affect your BAC include:

  • Weight
  • Age
  • Height
  • Metabolism
  • Gender
  • Food consumed
  • Type of alcohol consumed
  • How long you have been drinking, and
  • Medications.

Legal BAC in California

Whether or not your BAC exceeds the legal limit will depend on your age and the type of vehicle you’re driving.

Drivers Age 21 and Over: Drivers who are at least 21 years old will be considered legally intoxicated when their BAC registers at or above .08 percent.

Commercial Vehicle Drivers: Drivers operating a commercial vehicle are held to a higher standard and will be considered legally intoxicated when their BAC registers at or above .04 percent.

Drivers Under Age 21: Drivers who are not yet legally allowed to purchase or consume alcohol will be considered legally intoxicated when their BAC registers at or above .01 percent.

BAC Testing

The amount of alcohol in your system can be found in your blood and your breath. Police have devised various methods to determine your blood alcohol concentration.

Breath Testing

Breath tests, commonly referred to as breathalyzers, are the easiest way for police to administer BAC testing. In California, breathalyzers can be administered at the scene of a traffic stop. How do breathalyzers work? Police will ask you to blow deep lung air, which is a better indicator of your BAC, into a testing device. When your breath enters, the device will multiply the amount of alcohol in your breath by 2100. This number will be your blood-to-breath ratio. This ratio will tell police what the level of alcohol in your blood is at that moment.

Blood Testing

Blood tests are generally thought to be more accurate than breath tests because they simply measure the amount of alcohol in your blood without calculation or manipulation. This type of testing is often done away from the scene of a traffic stop, at a hospital or police station. While the measurement itself may be more accurate, the delay in administering this type of test can throw off the result.

Limitations of BAC Testing

Even though blood alcohol tests are scientific, they may not always be 100 percent accurate. Scientific tests can always be affected by a variety of factors. If your BAC registers at or above the legal limit, it is important to determine which factors may have affected the result. The following factors may limit the accuracy of a blood alcohol test:

  • Breathing patterns
  • Alcohol residue in the mouth
  • Medications
  • Radio frequency interference
  • Improperly administered tests
  • Delays in testing, and
  • Improperly stored samples.

Fighting DUI Charges in Los Angeles

Have you been arrested for a DUI in Los Angeles? Having a DUI on your record can make your life incredibly difficult. You will not only risk losing your license, but may also be required to serve time in jail, pay significant fines, and undergo mandatory counseling. You have the right to challenge your DUI and any BAC tests that were administered. Hiring an attorney to handle your case will increase your odds of success. It is important to act quickly, especially if you want to keep your driver’s license.  Contact Los Angeles DUI attorney Ambrosio Rodriguez today to request a free consultation and learn more.

To learn more, call our Los Angeles criminal defense law firm at 213-995-6767 or visit our contact us page to send us an email.

Last Updated on December 29, 2021