San Diego BAC Testing

In California, the arresting officer must tell you that you have the right to choose between different types of tests for alcohol. This usually means the choice between a Chemical Breath test, or a blood test. You will probably be given a series of field sobriety tests, such as walking a straight line and reciting the alphabet before being asked for a more scientific analysis. In some states you will be asked to perform a breathalyzer which measures gases in the breath. These results are susceptible to numerous problems, including false positives from people with diabetes and those who have worked with volatile chemicals. If you are offered a choice of tests, it is generally agreed that blood tests are the most accurate.

Implied Consent Warning

The main principle behind the state’s right to ask for a chemical test to determine your blood alcohol level is the implied consent law. It states that anyone with a driver’s license automatically consents to testing. No one has the absolute right to operate a vehicle. Every state has an implied consent law. Supreme Court rulings have decided that police may forcibly take your blood in order to test your blood alcohol levels, though on a practical level, that rarely happens. Most states rely on statutes that make refusing to test even more punishing than taking the test and failing. In California, you make a choice between the type of test you wish to take. If the facility only has blood testing, then you must use that type of test.

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Retrograde Extrapolation

One of the fancier methods the prosecution and the law uses to determine your blood levels at the time you were driving is retrograde extrapolation. This is a mathematical calculation of what your blood alcohol levels must have been when you were driving, given its current levels. This type of calculation is often made when blood alcohol levels, at the time of testing, are lower that expected. It is used to suggest that your levels must have been higher when you were driving (your metabolism was still in the ‘Absorptive Phase’).

The absorptive phase is the period when the body is actively absorbing alcohol into the bloodstream. Alcohol is absorbed in the stomach, the upper intestine and the lower intestines. The rate of absorption is the highest while in the upper intestine. In about one hour, ninety percent of the alcohol will have been absorbed into the bloodstream. The rate of absorption varies considerably from individual to individual. It also will vary according to the contents of the stomach at the time drinks are ingested. Because everyone’s metabolism is different and because the amount of food in your system can change the rate of absorption, retrograde extrapolation is very suspect. It is important to challenge such suppositions.

In order for the state to successfully use information gathered from blood, urine or breath testing, it must be sure the test is accurate. Blood alcohol testing is a complicated and technical chore. Because it is measuring small amounts of chemicals involved in a complicated chemical process, it is crucial for the state that the equipment be tested and calibrated frequently. It must also ensure that whoever administers the test follows all procedures exactly. This means that the person must have proper training, and if the law calls for it, re-certification at appropriate intervals. Because the test must be given under optimum conditions, the officer must arrange these conditions. There are many technical reasons why a given test could be inaccurate. If you’ve been charged with a DUI in San Diego call us today to schedule a consultation.