Patrick Silva 

San Bernardino & Riverside Counties

                     909-798-1500                   ​​​

California DUI: Chemical Testing

Learn about taking the blood or breath tests in California.






​Do you have the right to choose between a blood or breath test?

Yes, you have the right to choose but if one of the tests is unavailable, you are required to take the other available test. For example, if the police department’s breath tester is broken, you will be required to take a blood test. You may only opt for the less-accurate urine test in the highly unlikely situation where both blood and breath tests are not available. Despite the requirement that the police offer you a choice between blood and breath tests, the courts have refused to effectively enforce this provision. In one case, the police refused to give the suspected drunk driver a choice and insisted on a blood test. The court refused to exclude evidence based on a coerced blood test, thereby gutting the law allowing such a choice of any enforcement mechanism.

What if you have a medical condition that prohibits testing?

California law has an exemption for people taking anticoagulants for a heart condition or who have hemophilia – that is, they don’t have to take the blood test.

Which test should you choose?

Take the breath test if … If you had only one beer, glass of wine, or mild drink, your blood alcohol will be under 0.05%, a level so low that no sane prosecutor would try the case. Since results from a breath test (unlike those from a blood test) can be directly displayed on the measuring device right away, it will become clear that you’re sober and the police might therefore let you go.

Take the blood test if … Choose the blood test if you’re sure you’re below 0.08% or if it’s been less than an hour since you’ve finished your last drink (more, if you’ve eaten food). That’s because your body is still absorbing alcohol. When your body is absorbing alcohol, a breath test will give an erroneously high value. So, if you last drank less than an hour before you’re tested, don’t take the breath test

Can you demand that your lawyer or doctor is present?

The rule is that you do not have the right to have your attorney present for the test. You do have the right to an additional blood or breath test performed by an independent doctor, nurse, clinical lab technologist, bioanalyst, or any other person of your choosing. You have the right to have this person come down to where you’re being held to collect your blood, breath, or urine sample at your expense. Still, this is difficult to arrange, and is not usually useful, unless your own test results are much lower than the police test—a rarity unless the sample taken by the police got mixed up with someone else’s—and can be expensive if you want to use the results at trial, since you need to pay witnesses to testify.

Are you entitled to a printed copy of the test?

You have the right to “full ­information concerning the test.” This means you’re entitled to a copy of the results, plus a written explanation of the manner by which the analysis was performed. You or your attorney should request this information by letter within a week or two of your arrest. Also, if a blood test was taken, you have the right to have part of the preserved sample collected by the police tested by an independent laboratory.

Do breath test devices ever malfunction?

There is also the possibility of a malfunction in the breath-testing devices. To assure accuracy, the device must be calibrated with air containing known amounts of alcohol vapor every 100 tests or ten days, whichever is more frequent. The police department’s records should indicate how often the device has been calibrated, serviced, and used. A lapse in record keeping and/or police memory as to calibration and preparation of sample solutions can help your ­attorney establish reasonable doubt about the accuracy of the instrument. Other errors may result from the particular type of breath gas analyzer used. Because breath gas analysis is often inaccurate, you may be asked to take the tests two, or even three, times to produce a consistent result. Your failure to give them all the breath samples they want will result in your license being suspended by the DMV.

What if I must take a urine test?

The law no longer allows you to choose a urine test. You can choose only a blood or breath test. Only if the officer is unable to access a breath-testing device and unable to locate a trained technician to take a blood sample, can the officer insist on a urine test. The urine test is less accurate than the blood or breath tests, which is why the law was changed in 1999 to allow use of the test only when the blood and breath test are unavailable. For example, you can only take a urine test when a police department’s breath-analyzing machine is out of order and there is no professional available to take a blood sample. Indeed, you must take a urine test under these circumstances, since it’s the only test available.