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Blood Alcohol Concentration

When you are are pulled over by a law enforcement official because they suspect that you are driving under the influence of alcohol, they will try to convince you to take a breathalyzer test. A breath test is the most common method for measuring a person's blood alcohol concentration during a DUI arrest.

In California, blood alcohol concentration tests are used as the golden standard of drunk driving. The police will pull you over and try to administer field tests to determine whether you are intoxicated. Should your test results show that your BAC is .08% or higher (lower in some cases), you will probably be arrested and punished accordingly.

Harsh penalties are meted out to individuals who are convicted of driving under the influence of alcohol or drugs. Individuals who cause injuries to other people or damage to property while driving drunk will face even harsher punishments. Your blood alcohol concentration (BAC) result can become a scathing piece of evidence in the hands of the prosecution and it would be a shame if the result was inaccurate for whatever reason.

A drunk driving conviction can have devastating impact on your life as it will be listed on your permanent criminal record. This will most certainly affect your future employment and financial future as anyone who performs a background check will have access to this information.

What Exactly Is Blood Alcohol Concentration (BAC)?

Also referred to as blood alcohol level, blood alcohol content, or simply BAC, your blood alcohol concentration is the amount of alcohol present in a person's bloodstream. This is measured as grams of alcohol per:

  • 210 liters of breath, or
  • 100 milliliters of blood.

Your blood alcohol concentration increases proportionally with the amount of alcohol you consume.

It is important to know that although your blood alcohol concentration (BAC) is scientifically validated at the time of your arrest, an experienced San Diego DUI Attorney may still be able to defend you against the charges, especially if law enforcement did not follow the correct procedures for collecting and storing samples.

While these tests are considered an objective measure to determine whether you are fit to drive, it is not all that objective. The legal driving limit prohibits a person with a BAC higher than .08% from driving. However, according to experts, some people are only intoxicated when their BAC is .10% or more. On the other hand, anti-alcohol lobbyists claim that a person is drunk when their BAC reaches .05%.

California law (23152b VC) maintains that you are presumed to be under the influence if your BAC is .08% or higher. Commercial drivers may be arrested if their blood alcohol levels are .04%, and people under the age of 21 may not drive with any amount of alcohol in their bloodstreams. If a minor is stopped for suspicion of driving under the influence and their test is .01% or higher, they will be arrested. This zero tolerance policy regarding underage drinking is harsh on people younger than 21.

Arrested for a Blood Alcohol Concentration (BAC) Below .08%?

However, you could even be arrested for drunk driving (DUI) if your blood alcohol level is below .08%, since arresting officers have discretion in terms of determining whether you can safely operate the vehicle. After all, if you have used marijuana but not alcohol, your BAC will be 0%, but you may be too intoxicated to drive.

If an officer suspects that you are too impaired to safely operate your vehicle, he or she would have to observe you to determine whether you are exhibiting behaviors that are consistent with intoxication:

  • driving too slowly
  • driving erratically
  • driving on the wrong side of the road
  • swerving
  • turning too quickly
  • failing to stay with the traffic flow
  • failing to signal at turns

When you are stopped, law enforcement officers may ask you to step out of the vehicle and they may administer field sobriety tests. You are not required agree to field sobriety tests, as they will be used as evidence against you, but they are highly subjective and not necessarily accurate.

Some of the tests used - in addition to breathalyzer tests to determine blood alcohol levels - include:

  1. Walk and turn test - This usually includes walking heel to toe across a certain distance before the officer will instruct you to turn around and walk back. During this test, the driver will determine whether you are able to follow directions and whether you are able to maintain your u refuse a breathalyzer test or to perform FSTs, you will be taken to the police station where you will have to provide a blood sample. Refusing breathalyzer tests, field sobriety tests and the blood alcohol content (BAC) test, authorities may suspend your license for a year as the result of implied consent laws.

Many different factors can be used to determine your BAC, including your body weight, the amount of alcohol you have consumed, the amount of time you spent drinking, the type of drinking, and your gender. However, all these calculations can be affected by:

  • your breathing pattern
  • your physical health
  • whether you're taking medication
  • whether you're drinking water in between alcoholic drinks
  • whether you eat while you drink.

An experienced DUI attorney knows how to identify violations of the regulations and how to convince the judge or jury that the violations may be inaccurate due to the violations. It comes down to understanding the way in which breath and blood tests measure your blood alcohol concentration (BAC).

Understanding the Blood Alcohol Concentration (BAC) Breath Test

California's law enforcement use various breath tests to measure a person's blood alcohol levels during a DUI stoppage. Ultimately, the breath test captures a sample of your breath to calculate the levels. A breath testing device is designed to measure the level of alcohol contained in alveolar (deep lung) air, as that is considered the most accurate breath for this purpose.

When the alveolar air enters the breathalyzer device, the sample is multiplied by 2100 to calculate the blood-to-breath ratio. This amount then converts the detected alcohol level in your deep lung air to your BAC. However, various factors can cause your sample to be contaminated, namely:

  • alcohol in the mouth can be mixed with deep lung breath to fool the DUI breathalyzer test.
  • fermentation of food stuck between the teeth can be mistaken for alcohol by the machine.
  • digestive conditions such as GERD or acid reflux can affect the accuracy of the reading.
  • certain medications could cause you to become more intoxicated quicker.
  • an inconsistent breathing pattern can cause the test to be less accurate.
  • radio frequency interference from nearby electronic devices can affect the circuitry of the blood alcohol reader and result in an inaccurate reading.

An inaccurate Blood Alcohol Concentration (BAC) can result in a false accusation of driving under the influence, and you may be wrongfully arrested if the result shows .08% or higher BAC.

Blood Alcohol Concentration (BAC) Breath Tests and Title 17

California's Title 17 also offers guidelines for ensuring that DUI breath tests are as accurate as humanly possible. As such, the person administering the test must follow these Title 17 stipulations when performing the test:

  • Observe the person who will be providing the sample for fifteen minutes prior to the sample.
  • The person providing the sample may not drink, eat, regurgitate, vomit, or smoke in the fifteen minutes leading up to providing the sample.
  • Ensure that the sample contains air from deep in the lungs (alveolar air).
  • The breathalyzer device must be calibrated after every 150 uses or every ten days.

Depite these safeguards, mouth alcohol can still mix with the sample, thus contaminating it and resulting in a higher reading.

Likewise, if the operator is not sufficiently trained to use a specific breath testing device, the results may be compromised.

Understanding the Blood Alcohol Concentration (BAC) Blood Test

While the breath tests measures your BAC indirectly, the blood test takes a direct measure of the alcohol present in your bloodstream. This makes a DUI blood test the more reliable method for measuring a person's Blood Alcohol Concentration (BAC). However, the blood test is not necessarily fool proof. Just because the result of the test shows that your alcohol concentration is .08% or higher does not prove that it is accurate. A number of factors can affect the accuracy of the result, including:

  • when your blood was drawn
  • whether the correct protocol was used to draw the blood
  • whether the person who took the sample was adequately trained and authorized to do so
  • where the sample was taken - it must be done at a police station or doctors' office
  • whether the sample contained adequate amounts of preservative and anticoagulant to preserve its integrity
  • how the sample was stored.

As such, a Title 17 violation can become the cornerstone of your defense strategy and could result in a successful plea bargain for lesser charges, an acquittal if the case goes to trial, or perhaps even a dismissal of DUI charges levied against you.

Blood Alcohol Concentration (BAC) Blood Tests and Title 17

The California Code of Regulations (Title 17) sets forth certain rules of conduct which determine how the government should conduct blood alcohol concentration. The following rules apply to DUI breath tests, DUI urine tests, and DUI blood tests:

  • the blood sample must be drawn by an authorized technician
  • the draw site may not be sterilized using an alcohol-based sanitizing agent
  • the blood vial must contain the correct amount of preservative and anticoagulant to prevent fermentation or clotting as that will lead to false readings
  • the sample must be sufficiently mixed with the preservative and anticoagulant
  • no expired preservatives and anticoagulants may be used
  • the sample must be stored according to prescribed guidelines.

Title 17 Regulations for Blood Alcohol Concentration (BAC) Urine Tests

If for whatever reason a person is unable to provide a breath or blood sample, law enforcement may request a DUI urine test to determine whether he or she has been driving under the influence of drugs, marijuana or alcohol. Title 17 also caters to urine tests. Although urine tests are longer considered legally valid evidence for drunk driving, it is used in cases involving driving under the influence of drugs (DUID).

If you are pulled over for a DUI offense and asked to provide a urine sample, you must be given an opportunity to first void your bladder. The sample can only be taken twenty minutes or more later, or it may not be considered scientifically reliable.

Both urine and blood samples must be stored according to specific guidelines for a year, which gives you an opportunity to have your sample retested by an independent lab.

Since all of these issues can affect the accuracy of the Blood Alcohol Concentration (BAC). DUI blood tests typically produce consistently accurate results, but when you feel that you were unfairly stopped or that your test results were incorrect, San Diego DUI Attorney can help investigate the matter and challenge any inaccuracies stacked against you. Ultimately, your attorney will try to have the blood sample excluded from the evidence, and the charges against you reduced or dropped.

San Diego DUI Attorney understands that there are many reasons why a Blood Alcohol Concentration (BAC) may be inaccurate. We will try to prove that you were under the legal blood-alcohol limit while driving your vehicle, but that your body may have absorbed alcohol in due to one of the reasons above by the time your Blood Alcohol Concentration (BAC) test was performed. Contact San Diego DUI Attorney at 619-535-7150 to discuss the specifics of your case.

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