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Blood Split Motions in California

In California, drivers arrested for driving under the influence (DUI) are required to submit to a chemical test to check the blood alcohol concentration (BAC) in the bloodstream of the arrested driver. An arrested driver has a choice between a breath test or a blood test. Take note that you can refuse to submit to a chemical test altogether, but this can have a negative impact on your DUI case.

If a driver chooses to get a blood test, Title 17 of the California Code of Regulations[1] allows arrested drivers to obtain a portion of the blood sample taken from them so they may have it independently tested. To be able to do this, a motion is filed in court called a "blood split motion."

What is a blood split motion?

As mentioned previously, a blood split motion is a motion filed in court so an arrested driver may legally obtain a portion of the blood sample taken from them after arrest. You can then now have an independent laboratory conduct testing on the blood sample.

By law, blood samples taken from an arrested driver must be preserved for one (1) year by either the forensic laboratory, law enforcement agency, or coroner/medical examiner’s office in possession of the original sample.[2]

Is blood split motion available for breath tests or urine tests?

As the name implies, blood split motions do not apply if you elected to take a breath test because there is yet no way to save or preserve a breath sample taken after a lawful arrest.

On the other hand, blood split motion is available for persons who took a urine test. Although urine testing is not the primary mode of measuring BAC, urine tests are sometimes done when both breath test and blood test is unavailable or possible (driver has a medical condition which prevents the test or in extreme cases of drunkenness when a breath or blood test cannot be taken). With a urine test, there is a sample that can be preserved so the defendant in a DUI case can ask for a portion of the sample for independent testing.

How does a blood split motion help in DUI defense cases?

Legally obtaining the remaining blood sample for independent testing is a defense strategy employed in DUI defense cases. It can have a great impact on a DUI case because and independent test on your blood sample opens up the possibility of contesting the findings of the laboratory who initially conducted testing on your blood. This an important defense strategy because chemical tests obtained by law enforcement are presumed to be accurate and it is up to the defense to prove that the results of the test, was in fact, not accurate.

Having the blood sample independently tested may show that there is a lesser BAC, or that the blood sample has been contaminated, or there is not enough anticoagulant and preservatives added to preserve the blood,[3] and other similar circumstances that can only be shown by having an independent test done.

In what type of DUI cases is the blood split motion relevant?

Blood split motions can be relevant in all types of DUIs as it can create reasonable doubt regarding the actual BAC. It becomes even more so useful in DUI cases where a legal limit for BAC has been set, particularly:

  • Non-commercial adult drivers = 0.08%[4]
  • Commercial drivers (Ex. Delivery service drivers, etc.) = 0.04%[5]
  • Those who take “passengers for hire” (Ex. taxi drivers, ride-sharing drivers) = 0.04%[6]
  • Underage drivers = 0.05%[7]

With the legal limit for BAC being set in California, it is still possible to be arrested and charged with a DUI even if your BAC is below the legal limit.[8] The reason for this is that the law considers you as someone “under the influence” if, as a result of drinking or taking drugs, your driving was impaired, even if your BAC was not on or above the legal limit.

Can the results of independent testing hurt my case?

Sometimes the results of the independent test do not show a result that can be favorable in your case. Sometimes it merely confirms the findings of the initial test done by the law enforcement agency or sometimes it can even show a higher BAC. In situations like these, the results of independent testing cannot hurt your case as you are not obliged to present these results as part of your evidence.

What happens if I get my blood sample and I do not have independent testing done?

This will not affect your case as you are not required or obligated to have independent testing done or even present the results as part of your defense evidence.

How to initiate a blood split motion?

By law, you have a right to obtain your remaining blood sample so you can have it independently tested. To initiate this process, your lawyer can make an informal request to the prosecutor in your case for the release of the sample. By law, the prosecutor has to disclose all evidence obtained in a criminal investigation to the defendant.[9]

The prosecution has fifteen (15) days from the time the request is made to turn over the sample to the defense.[10] If the prosecution fails to turn over the sample, your lawyer can also file a motion in court for the release of the sample. Sometimes this is also required so that whoever has current possession of the remaining sample can legally turn it over to the independent laboratory that you have chosen.

No Judgment, Only Professionalism

If you have been arrested or charged with a DUI, it is all-important to hire an experienced, aggressive, and seasoned private West Covina defense lawyer to fight your case. We always make our clients feel right at home and we encourage you to take comfort in the fact that you have a dedicated advocate on your side at Coimbra Law Firm, APC. Our highly-experienced lawyers at Coimbra Law Firm, APC will help ensure that your Constitutional rights are protected. Each of our clients will receive personalized attention, complete discretion, and trained staff working to provide the best legal assistance available.

Our only job is to defend you with the maximum competence, diligence, and zealousness. Do not hesitate to contact us and call (626) 827-7222 for the representation you need.


[1] 17 California Code of Regulations §1219.1 (f) – “In order to allow for analysis by the defendant, the remaining portion of the sample shall be retained for one year after the date of collection.”

[2] Id at §1219 (f) (2).

[3] Id at §1219 (d) (2)

[4] California Vehicle Code § 23152 (b)

[5] California Vehicle Code § 23152 (d)

[6] California Vehicle Code § 23152 (e)

[7] California Vehicle Code § 23140

[8] California Vehicle Code § 23152 (a)

[9] Penal Code §1054.1 (c) and § 1054.5 (b)

[10] Id at §1054.5 (b)

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