When is Chemical Testing Conducted in a DUI Case?

When a driver is lawfully arrested on suspicion of driving under the influence, California law requires that the driver submit to chemical testing. Drivers who are suspected of driving under the influence of alcohol will be given the option of taking either a breath or blood test, while those suspected of driving under the influence of drugs must take the blood test as there is no breath test that can measure for the presence of drugs. As soon as the driver is arrested, the clock is ticking and the police will often want to conduct testing as soon as possible to ensure the test results reflect the driver’s BAC near the time of driving.

When a driver is arrested for DUI, he or she will be read a refusal admonition and will be given the option of taking either a breath test or a blood test. The police may encourage the driver to choose the breath test. This is because the breath test is easier to conduct, as the Breathalyzer machine is often located at the police station and a test can be completed within minutes. The blood test is usually conducted at a hospital or laboratory and the suspect would have to be transported to this location by an officer. The test must be conducted by a qualified medical professional and it may be necessary to wait until one is available.

It is illegal to drive while under the influence of drugs or alcohol or with a BAC of 0.08 percent or higher. Because testing is conducted after a driving has occurred, the effects of alcohol metabolism may affect the testing results. After consuming alcohol, a person’s BAC will steadily rise during the absorption phase, level off and then fall during the elimination phase.

If the driver had not recently consumed alcohol and was going through the elimination phase at the time of driving, his or her BAC will steadily fall and may be under 0.08 percent by the time chemical testing is conducted. Because of this, the police will not waste time in conducting chemical testing. Officers will also ask the defendant to provide a breath sample on the portable preliminary alcohol sensor (“PAS”) device while in the field. This can be used as evidence of a falling blood alcohol level if the driver later has BAC results under 0.08 percent.

If the driver is in the absorption phase, any delay in testing may result in BAC results that are higher than the driver’s actual BAC at the time of driving. The defendant’s attorney may be able to argue that the defendant’s BAC was actually under 0.08 percent at the time of driving but only tested higher due to a rising blood alcohol level. It may be necessary to use a toxicology expert to explain this phenomenon and show how the defendant did not drive with a BAC in excess of the legal limit.

The DMV will consider test results taken within three hours of driving as indicative of a driver’s BAC at the time of driving. If testing did not occur within this three-hour window, the DMV will require other evidence or expert testimony using retrograde extrapolation to determine the driver’s BAC at the time of driving. The expert will consider factors such as the driver’s answer to time when alcohol was consumed and the results of the PAS test when determining whether or not a driver had a BAC of 0.08 percent or higher at the time of driving.

If you have been arrested for DUI, it is critical that you speak with an experienced DUI lawyer right away. As a former Deputy District Attorney with over 14 years of prosecutorial experience, Michael Kraut is highly effective at fighting DUI charges both in court and before the DMV.

For more information about DUI chemical testing, and to schedule your free consultation, Mr. Kraut can be reached 24/7 at 888-334-6344 or 323-464-6453.