Drunk driving investigations often include the officer asking the suspect if they will submit a breath test in the field. This test is called a PAS, or preliminary alcohol screening, test which measures your blood-alcohol content. It is another field sobriety test, or FST, that the officer uses as a tool to help determine if the driver is under the influence of alcohol.
If you are not on probation for a prior DUI matter, this test is optional. If you are on DUI probation, a standard term of probation is for the probationer to submit to any test at the request of a peace officer for detection of alcohol and/or drugs. If you refuse such a test, you will be in violation of your probation terms.
It is not advisable for anyone who is not on DUI probation to submit to the PAS test or any other FST's. The officer is simply building a case against you.
Once an officer has probable cause to arrest you for drunk driving, you will be asked to submit to a breath, blood, or urine test. Under California law, (Vehicle Code Section 23612), licensed drivers have given "implied consent" to provide a chemical test if lawfully arrested. Therefore, you must submit to one of the tests, otherwise it will be considered a refusal and the officer will forcibly take a blood sample from you. There are additional penalties with the California Department of Motor Vehicles and in the California courts for refusing such a test.
In San Diego County, if you choose to do the breath test, it is often done on an Intoxilyzer machine.
After the test is completed, the officer must give you an admonishment called a Trombetta Admonishment. This advises the suspect that their breath sample is not retained and therefore cannot be retested. The defendant is then offered an additional blood test which is stored at the crime lab. The defense can later retest that sample at an independent lab to test its accuracy. Taking that second test could backfire because there are now two separate tests that may confirm the same result. It is best to just choose one test. Then the defense can attack the testing process, procedures, and results of the one chosen.
The above blog article is by no means all-inclusive and is not legal advice. Laws may change and may not apply to your case. For the latest information or to get legal advice, speak to a DUI attorney in your area.