Should I take a breath or blood test if I get pulled over for a DUI?


A typical handheld PAS device.

This is Dan Smith, Supervising Attorney at San Diego Defenders. I am asked by many friends whether it is better to take a breath test or blood test. First of all, I tell them, you must understand that if you are arrested you must take a breath test or a blood test - YOU MUST CHOOSE ONE OR THE OTHER UNDER THE IMPLIED CONSENT LAW IN CALIFORNIA! We have had an alarming number of cases where our client was told by the officer that they "would just get a warrant" for the blood test and are then charged with a refusal. It is important to ask the officer two questions 1. "Am I under arrest for DUI?" If the answer is yes, then tell the officer "I choose to take one of the chemical tests voluntarily."

With that being said, it is also important to know the difference between a PAS or hand held breathalyzer, the most common of which is the  AlchoSensor model 4 and 5 in San Diego County. A "PAS" device is designed to test for the presence of alcohol and not admissible in court. If you are asked to take a "test" then it is smart to ask the officer if the device is a PAS or if you are under arrest and the PAS is the actual "implied consent" chemical test.

You do not have to take a "preliminary alcohol screening" breath test using a handheld device PAS device no more than you are required to take the FST's of Field Sobriety Tests (more on that in a different DUI Defense). PAS hand held breathalyzers are particularly inaccurate and subject to gross errors. There are exceptions, the most common one is if you are an off-road enthusiast and are stopped by Law Enforcement. If so, simply inquire if the officer is giving you a chemical test under the implied consent law. If you are confused by the use of the words "implied consent" or chemical test, don't hesitate to call us at San Diego Defenders and we will go into further detail.

Another exception to PAS rule is if you are on probation for a DUI or if you are under 21 years old. If so,  you MUST take the hand held test if the officer thinks you are driving after drinking. If you are not on probation or underaged, don't be fooled. The police may say they think you are under the legal limit or you are borderline and will let you go if you take the test and have a low result. Don't be a sucker. They have already decided to arrest you and they are only trying to get more evidence against you. If you are arrested, as explained above, you will still have to take a chemical blood or breathe test whether you take the hand held PAS test or not.

Blood tests are usually more precise than breath tests. Blood tests can be re-tested, and we do that often for San Diego Defender clients, when we believe that we gain an advantage for our clients. A breath alcohol test is only an approximation of what is actually in your blood and cannot be re-tested. In fact, the officer must read a "Trombetta-Hitch" warning that a sample will not be saved for future testing. The breath machine measures how much alcohol is in your breath and then extrapolates what is in your blood based on an assumed average ratio.

If you are certain you only had a very small amount to drink, one beer, one 4 ounce glass of wine, one ounce to an ounce and a half shot of hard alcohol, take the blood test. It is usually more accurate and will not be thrown off by a burp. If you had more than that to drink, take the breath test. It will give your DUI lawyer more to work with. Remember, blood tests can be wrong too if the sample is not handled properly. 

If you would like more information on your breath or blood test results from your DUI, please feel free to contact our office at (619)258-888 and speak with one our experienced DUI attorneys.