What Is BAC?

BAC stands for Blood Alcohol Concentration, a measure of how much alcohol a person has in their system. BAC is measured in grams of alcohol/milliliter of blood. Police officers often use Breathalyzers to measure a person’s BAC. If this device registers a BAC of 0.08% or higher, an officer can arrest you for driving under the influence (DUI).

A Los Angeles DUI lawyer can help if you face DUI charges. They can challenge breath test results using a variety of DUI defense strategies. An attorney can also build a defense to help minimize your sentence if your charges result in a conviction.

breath test to measure bac

A breath test to measure BAC. Blood Alcohol Measurements tell the state of your BAC if you’re too intoxicated to drive.

Why Is BAC Used to Measure Intoxication?

Any alcohol you drink ultimately ends up in your blood. As you consume an alcoholic drink, your body absorbs the alcohol into your blood through the stomach lining and the small intestine. This is a gradual process since alcohol takes time to be absorbed. As more of it gets into your blood, more of it reaches your brain, and you become more impaired.

BAC (“blood alcohol concentration” or “blood alcohol content”) is a way of measuring how much alcohol you have in your system. It’s widely used by courts to draw the line between “intoxicated” and “sober,” but it is not a perfect metric.

A breath test or breathalyzer is often used to measure BAC. Blood alcohol measurements tell the current state of your BAC. Under California Vehicle Code 23152, a BAC of 0.08% or more indicates that you are too intoxicated to drive.

Why Does BAC Vary From Person to Person?

Two different individuals can drink the same amount of alcohol and end up with a different BAC. The difference depends on:

  • Your age and weight
  • How much food you consumed
  • What type of alcohol you drank
  • Whether it was carbonated
  • How long you took to drink it

Despite these differences in alcohol consumption, if two people have the same BAC, they will experience roughly the same level of impairment or intoxication. Therefore, it’s used as a standard measurement in DUI cases.

Alcohol tolerance can also make it difficult to know how much you’ve been drinking. A standard drink can affect two people very differently. People who drink regularly can ingest more alcohol before they feel impaired. For the law, how intoxicated you feel does not matter. It’s how you act and what your BAC level is that matters.

How Is BAC Measured?

BAC is normally expressed as a percentage. For example, the legal “limit” for most drivers in California is 0.08% BAC, although sometimes, a much lower BAC will still count as a DUI. BAC percentages are really grams of alcohol per milliliter of blood, which you may see in a test report, but it will reflect as a percentage.

There are two primary ways the police may measure your BAC. At the scene of a traffic stop, they may use an alcohol breath test with a breathalyzer machine. The science behind breathalyzer and chemical tests hinges on the relationship between the concentration of alcohol in a person’s breath and their BAC.

If an officer takes you to the station or a hospital, they can also do a blood test or a urine test to determine your BAC. This requires drawing blood or collecting a urine sample. 

How Accurate Are BAC Chemical Tests?

BAC can be misleading, even when confirmed with a test. Often, BAC will continue to rise long after you stop drinking because you haven’t absorbed all the alcohol yet. That means you were less drunk when you were pulled over than you were hours later at the breath test. In some cases, a rising BAC defense is valid for DUI charges.

Why Would You Be Charged With DUI Even With a Low BAC?

California’s DUI laws are really about getting unsafe drivers off the road. Under California law, you exceed the legal limit if you have a BAC of 0.08% or higher. You are intoxicated even if you are driving perfectly. That’s the line the law has set for intoxication under any circumstances, even if your alcohol tolerance is high.

However, if you are driving unsafely and the police can find a little alcohol in your system through a BAC test, they can try to pin your unsafe driving on your alcohol consumption. They may not even need the test if there is other evidence of drinking or drug use.

For example, some officers use field sobriety tests, such as the one-leg stand test, to determine if a driver is impaired. Considering how inconclusive chemical tests can be, you can imagine the subjective nature of field sobriety test assessments. A sober person with mobility issues might not even pass such performance assessments. 

What Happens if You Refuse a BAC Chemical Test?

California Vehicle Code 23612 is the law that requires all drivers to submit to chemical testing, such as a breath test or blood test, if they are arrested for DUI. Unfortunately, if you refuse a chemical BAC test, whether at the scene of the traffic stop or in custody, you can face a one-year license suspension

If you are eventually convicted of DUI, your refusal of a BAC test can also result in additional penalties, such as increased fines and jail time. 

How a Los Angeles DUI Lawyer Can Challenge the Results of a BAC Test

When it comes to DUI cases, the blood alcohol concentration (BAC) test results are often key evidence for the prosecution. However, a DUI lawyer can challenge the accuracy and admissibility of these BAC tests in various ways:

Attacking the Testing Process

BAC tests, whether blood, breath, or urine, must follow strict protocols and regulations. A lawyer can scrutinize whether the officers and testing staff adhered to proper procedures such as:

  • Using properly calibrated and maintained equipment
  • Allowing the required observation period before breath tests
  • Using certified staff with up-to-date training and qualifications
  • Following Title 17 rules on test administration and sample handling

Any deviations from the mandated processes can undermine the test’s reliability and admissibility.

Medical Defenses

Certain medical conditions like acid reflux, diabetes, or blood-mouth alcohol contamination can falsely elevate BAC readings. A DUI attorney can obtain medical records and expert testimony to demonstrate these factors.

Rising Blood Alcohol Defense

The human body takes time to fully absorb and metabolize alcohol. If the test captured a rising BAC that was lower while actually driving, an expert can estimate what the person’s BAC would have been earlier.

Challenging the Legal Stop

If the initial traffic stop lacked reasonable suspicion or probable cause, a DUI lawyer could get the BAC test results fully suppressed as “fruit of the poisonous tree” from an unconstitutional stop.

Questioning Test Accuracy

Errors in calibrating equipment, expired solution mixtures, contaminated test ampoules, radio frequency interference, and other factors can all lead to inaccurate BAC readings that good attorneys can attack.

From meticulously cross-examining the test administrators to highlighting deviations from protocols to presenting expert analysis, a tenacious DUI lawyer will scrutinize every aspect of the BAC testing looking for issues to undermine and exclude the results. Having this kind of vigorous legal defense can mean the difference between a DUI conviction and having the case fully dismissed.

Seek Help for DUI Charges in Los Angeles

If you have been charged with DUI, an attorney in Los Angeles can help. Get your FREE consultation today and start building your defense. They can explain more about what BAC is and how they can challenge your test results.

Contact us online or call us for your free, confidential consultation today.

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