Blood tests are one of the most common types of chemical tests used in California DUI cases, along with breath tests and urine tests. Normally, you will be asked to take one type of test after you are arrested for DUI, as part of being processed by the police. California has an “implied consent” law which says you have agreed in advance to take this test, as a condition of driving. If you refuse to take the test you will face penalties.
How does a DUI blood test work?
All DUI blood samples must be taken by a qualified technician. If the police do not have such a technician on hand, and are not willing to transport you to one, they cannot take a blood draw. Additionally, police must usually obtain a warrant for a blood draw, even though you are required to consent by state law. Police can often get these warrants very quickly, as it is a routine part of a DUI arrest.
Before the blood draw, police will explain that you are required to provide a sample and that there are penalties for refusing. They will then ask you to submit to the blood test. If you disagree or delay in any way it will count as a “refusal” which carries adds jail time and a longer license suspension to your normal DUI penalties. You are allowed to request a different type of test, such as a breath test or urine test. However, if this other test is not available, you must submit to the blood draw.
Once you agree, the technician will swab your arm and use a needle to draw blood. The amount taken is relatively small, and the draw is usually over in less than a minute. Most people do not feel faint or woozy after a DUI blood draw.
If you have a medical condition that makes a blood draw unsafe, you should tell police this, and this does not count as “refusal.” They should use a different kind of test.
Are DUI blood tests reliable?
If properly taken, a DUI blood test is a reliable way to tell your blood alcohol concentration (BAC), or to detect some drugs in your system. This is because it captures the exact chemical content of your blood at the time of the draw. Blood tests are also considered more reliable than breath tests because the sample can be re-tested multiple times to verify the results of the first test. This makes them more trusted than other chemical tests.
However, there are many ways that a blood test can give an inaccurate result. These include:
- Blood sample was taken too long after the initial arrest (rising BAC)
- Sample was contaminated and fermented, raising its alcohol content
- Sample was improperly stored and fermented
- In a marijuana DUI, the levels of THC in the body do not necessarily reflect how impaired you are
This means that the results of a DUI blood test are not always reliable.
Can I have a lawyer challenge my DUI blood test?
Yes. Your lawyer can challenge the validity of the test on any of the grounds above, as well as for procedural reasons. In some cases, the test may be considered contaminated and your lawyer could get the judge to exclude the evidence from your case. That means that the prosecution has to build a case against you with absolutely no blood evidence that you were intoxicated. This is often when the prosecutor offers to reduce the charge to something less serious.
Can I have a different laboratory test the blood sample?
Yes. This is called a “split.” California allows you to request that the blood sample be split, so that half of it is turned over to an independent laboratory of your choosing. This allows you to verify (or dispute) the result that the state’s laboratory gets. In some cases, it can even reveal a discrepancy in how the state handled or tested the sample.
What if the technician used an alcohol swab before the blood test? Does this affect the test result?
Yes. Technicians are not supposed to do this, and doing it is a violation of Title 17 regulations. Alcohol swabs contain ethyl alcohol, and some of this alcohol can enter the syringe during the draw and thus contaminate the sample. Your blood test could come back showing a much higher BAC than what you really had because of the ethyl.
Technicians should use a non-alcoholic swab. It is important to disinfect the blood draw area before the test, without contaminating the results.
Is refusing the test a good idea or a bad idea?
Refusing the blood test is illegal. You should comply with officer’s instructions and follow the law. Obviously, submitting to the blood draw means you may be giving police evidence that they can use against you. But refusing it also makes you look guilty, and complicates your case both in court and with the DMV. Remember that DUI blood tests can be disputed after the fact. It’s better to wait and let your lawyer fight the blood test.
How does a DUI lawyer fight the blood test results?
Your lawyer will look at:
- The timing of the blood test and how much time elapsed since your arrest
- The blood test results and how close they are to the “legal limit”
- Who performed the blood draw, and records about how it was performed
- How the sample was stored and whether any materials were expired
- Which lab analyzed the blood sample and what their procedures are
They may also request the split and do an independent analysis on the blood. Often, one or more of these steps will produce evidence that can get the blood test thrown out.
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