Drug and Criminal Defense in San Diego
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Effects on BAC

When someone is arrested for DUI in California under Vehicle Code Sections 23152(a)(b) and VC sections 23153(a)(b), felony DUI, they are provided three options under VC 231612: They can provide a blood, breath, or urine sample. Urine is typically offered (suggested) if the arresting agency suspects that drugs are present and a blood test is unavailable.

If a breath sample is provided, and that sample comes back over .08% BAC, an arrest will likely occur. California Title 17 requires that the breath sample measure the alveolar air – that is, deep lung air. Oftentimes, there is a question as to the accuracy of a breath sample. Remember, the breath machine is supposed to measure the amount of alcohol in the blood. This is done indirectly, however, by measuring the amount of alcohol in the breath (BrAC).

Partition Ratio:

The partition ratio converts alcohol measured in the breath to estimates of alcohol in the blood. This measure is in direct proportion to the amount of grams of alcohol to every 1 milliliter of blood. Therefore, 2100 milliliters of breath will contain the same amount of ethanol as 1 milliliter of blood.

One issue is that partition ratio varies greatly among individuals – from 1300:1 to 3100:1 or more. This may greatly impact the BrAC and can place someone over the legal limit of 0.8% BAC, even if they are not.

Mouth Alcohol:

Alcohol contamination in the mouth can also negatively impact the BAC. This may be a problem if the person recently consumed alcohol, vomited, regurgitated, or burped. This is supposed to be mitigated by Title 17, which requires a 15 minute observation period before a breath sample is provided. However, if there is a Title 17 violation, the breath sample may be affected.

Medical Issues:

Chronic Obstructive Pulmonary Disease (COPD) is a group of lung diseases that impacts airflow through the bronchial tubes. As a result, airflow is partially blocked and thus does not always correlate with BAC.

Diabetes is another medical issue that may affect BAC. Diabetics sometimes eliminate ketones (acetone) as a waste product, because some cells oxide fats for fuel. If a diabetic with hypoglycemia develops ketoacidosis, acetone in the mouth can make the breath smell of alcohol. Consequently, a high BAC reading may result because the breath testing machine mistakes the acetone for ethyl alcohol.

There are other reasons that BAC may be falsely elevated. To receive a free consultation on your DUI charge, please contact my office today.