Evidential Breath Test

Once you are arrested for DUI in Ventura County, and throughout California, you have the choice between a breath or blood test. The breath test that is given after arrest in a Ventura County DUI is called an evidential breath test. The reason for this is that the breath machines used at this stage print out a ticket-like strip that will be used as evidence against you when the District Attorney prosecutes you for Driving under the Influence of alcohol. There are two devices that are used at this stage of a DUI in Ventura County. The portable device that can be used on the side of the road is the Alco-Sensor IV XL. This device is checked out by a limited number of officers within each law enforcement agency, and is carried in their vehicles within a small plastic yellow box. The other evidential breath test device used in a Ventura County DUI is the Intoxilyzer 5000 EN. These are stationary devices that are located at the various police stations throughout Ventura County, as well as at the Ventura County Main Jail.
There is an entire set of manufacturer guidelines as to how these devices are supposed to be used, and there is a huge body of law that controls how the machines are to be operated, maintained, and calibrated. Title 17 of the California Code of Regulations controls the use and operation of the devices that are used to measure one’s alcohol level in a Ventura County DUI. While Title 17 is very complex, the important elements to remember for DUI purposes is that the breath machines have to be tested for accuracy every 10 days or every 150 tests. In Ventura County, no machine has ever been used 150 times within a 10 day period, so the devices are at least supposed to be checked every 10 days. The method by which the accuracy checks are performed is for a beaker of alcohol to be heated up to the temperature of a human breath, and then blown into the device. The beaker of alcohol is at a fixed and known percentage, which is usually about a 0.11% or 0.12%. In order to qualify as an accurate device, the breath device results must be within .01% of the alcohol in the beaker.

One of the things we do in every Ventura County DUI case is to subpoena the maintenance and calibration logs that show how the breath device that was used on you was performing during the time period that you were arrested. Once we receive the logs, our experienced Ventura County DUI goes through them with a fine tooth comb to ensure that the device was in compliance with Title 17.