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Understanding DUI Blood Tests in California

Posted by Richard Wagner | Feb 14, 2024

Can I Challenge DUI Blood Test Results?

Drunk driving or drugged driving in California is a serious criminal charge. During a DUI investigation, an officer may request a blood sample.

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blood test alcohol drugs

This is especially true when an alleged suspect refuses a breathalyzer test or a police officer believes the suspect is intoxicated by drugs.

If you do not agree to it, the police will get a search warrant, and at that time, a blood sample will be taken with or without your consent.

A lot of confusion surrounds what your rights and obligations are regarding drunk driving and blood tests.

To do one thing and not the other can have a significant impact on any criminal charges filed against you or DMV penalties imposed on you in California.

DUI Defense Attorney Richard Wagner wants to ensure you are informed and understand both your rights and the consequences that flow from missteps taken when encountering the police during a DUI investigation in California. Contact him today at (714) 721-4423 to schedule a FREE Consultation. 

What are DUI Blood Tests?

DUI blood tests are chemical tests used in California at the direction of the police to determine whether and to what extent an individual unlawfully has alcohol or drugs in their system. It is used most often in three circumstances:

  1. The alleged drunk driver has refused a breath test; and/or
  2. The police believe the driver might be under the influence of drugs, which can include prescription medication or any type of illicit drug;
  3. The alleged drunk driver has chosen to take the blood test rather than the breath test after being arrested for DUI. 

A blood test is also much more intrusive than a breath test. With breath tests, you simply blow into the testing machine. With urine tests, you urinate into a cup. With blood tests, however, a qualified medical professional must draw blood to collect a test sample.

Can I Refuse a Blood Test in California?

The simple answer is yes. Keep in mind, however, that a refusal in California can have significant consequences. Read about Refusing DUI Breath and Blood Tests.

The same is true even if you are never convicted of an intoxicated driving offense in California because you will still face DMV administrative penalties. Read About DMV Administrative Penalties

The problem is this: VC 23612 is the implied consent law.

When you get a driver's license and drive anywhere in California, you have implicitly implied to agree to obey the laws of California. Basically, by agreeing to obey the rules of the road, you also implicitly agree to chemical tests. However, the United States Supreme Court in Missouri v. McNeely (2013) 569 U.S. 141, transformed implied consent laws, holding you can withdraw your consent to a blood draw. 

When Are DUI Blood Tests Allowed in California?

Unless the prosecution can prove that there were exigent circumstances, or you gave lawful consent, or the police got a search warrant, the police cannot force you to give a sample of your blood.  

  • Exigent Circumstance - natural dissipation of alcohol in blood must be determined on a case-by-case basis
  • Express Consent must be without coercion
  • Implied Consent - Prosecutor must prove by preponderance of evidence by your conduct or statements. Also, California has an implied consent statute VC 23612. However, you may withdraw the VC 23612 consent. 

Thus, if you are arrested for drunk driving and are asked whether you will take a breath or a blood test but refuse, there are DMV administrative penalties in play. These penalties include license suspension or revocation with no ability to get a restricted license.

If you refuse to give a blood sample (or refuse a breath sample), the police usually will get a search warrant to collect your blood sample. In the end, if you "refuse", the police will most likely get your blood sample.

Can a DUI Blood Test In California Be Wrong?  

Blood tests can determine blood alcohol content (BAC) level and they can also identify specific drugs and the amount of those drugs in your system.

However, they can still be unreliable when specific issues are present.

Everyday situations that lead to reliability issues with a blood test result in DUI cases in California include:

  • Too long of a waiting period between arrest and administration of the blood test
  • Microbial contamination of the blood sample - Fermentation 
  • Improper preservation or storage
  • Improper transportation of the sample
  • Gap in the sample's chain of custody
  • Human error (sample mix-up, mislabeling during analysis)
  • Drawing of the blood sample by an unqualified person
  • Not drawing the blood sample according to accepted medical practices

In addition, the technology and machines used to analyze the blood samples could have problems making the results unreliable. Instrumental factors such as detector, injector, and/or temperature variations can affect accuracy. These machines require regular maintenance but are often neglected. 

Fermentation in the blood vial?

Alcohol can be made on its own in the blood vial through what scientists call Fermentation. This is when the glucose in your blood combines with microorganisms causing alcohol to be produced. The machines crime labs use to test your blood cannot tell if the alcohol found in your blood came from fermentation or from the alcohol you consumed.  

DUI defense attorneys in California who have the right experience, knowledge, and skill in these types of cases will be able to identify unreliable blood test results. Motions can be timely filed and strategic cross-examination of the relevant witnesses can be used in your defense.

How DUI Defense Lawyers Beat DUI Blood Tests

DUI blood tests can be disputed and challenged under certain circumstances. A defense lawyer should identify when those circumstances are present and take appropriate action.

With DUI blood tests your defense attorney can file motions to show the conditions:

  • subjected you to “unjustified element of personal risk of infection or pain"1 
  • and evaluate whether “the draws were performed in a manner which created undue harm or risk ”2 and,
  • Whether you were "exposed to an unreasonable risk of infection or pain?”3   

The United States Supreme Court clarified what makes a blood test "performed in a reasonable manner." The Court noted the "blood was taken by a physician in a hospital environment according to accepted medical practices." We are thus not presented with the serious questions which would arise if a search involving use of a medical technique, even of the most rudimentary sort, were made by other than medical personnel or in other than a medical environment -- for example, if it were administered by police in the privacy of the stationhouse. To tolerate searches under these conditions might be to invite an unjustified element of personal risk of infection and pain.4

Your blood must have been taken in a reasonable manner.

Was My Blood Drawn According To Accepted Medical Practices? 

To determine whether your blood draw was taken in according to accepted medical practices, consider whether: 

  • the phlebotomist washed their hands with antibacterial soap and water5
  • you were seated comfortably in a chair
  • your arm was positioned horizontally or slanting slightly downward
  • your arm was on a suitable support (armrest, table, etc.)6
  • they used the preferred venipuncture site - the antecubital fossa (veins on back of hand are also acceptable)7
  • the tourniquet was left on your arm for more than one (1) minute8 
  • the phlebotomist inspected all supplies for possible defects and applicable expiration dates9
  • the phlebotomist put on new gloves10
  • the phlebotomist cleansed the puncture site to minimize contamination and patient infection11
  • a nonalcohol-based cleanser was used12
  • the area was allowed to dry
  • if it was necessary to repalpate the site, the site was cleansed again13
  • your arm or other venipuncture site remained in a downward position to prevent reflux or “backflow” from the collection tube into your vein14
  • the tourniquet was released as soon as blood flow was established to minimize hemoconcentration15
  • the vial was filled to the maximum stated volume (until the vacuum was exhausted)16 
  • after completion of the draw, the blood vial was gently inverted17
  • the phlebotomist probed unnecessarily on your arm with a needle. They should not have stuck you more than two (2) times18

Finding the right DUI defense lawyer in California will be key to a successful outcome in your DUI case.

Contact a Skilled DUI Defense Attorney in California Today

DUI Defense Attorney Richard Wagner understands the complex nature of California intoxicated driving laws, the technical and scientific aspects of blood tests, and how to strategically fight the allegations to get the best outcome in your unique case.

He wants you to know that just because you are charged with DUI offenses, it does not mean you will be found guilty. You can successfully defend against these types of charges, but you need a DUI defense lawyer who can help you do it. Call him today at (714) 721-4423 or fill out an online form to schedule a FREE Consultation.

1 People v. Ford, (1992) 4 Cal.App.4th 32, 38.

2 People v. Mateljan, (2005) 129 Cal.App 4th 367, 376.

3 People v. Sugarman, (2002) 96 Cal. App. 4th 210, 216.

4 Schmerber v. California, (1966) 384 U.S. 757, 771-772.

5 Clinical and Laboratory Standards Institute (CLSI), Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. 2.6 p. 12.

6 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. 2.8 p. 13.

7 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. 2.9.2 p. 15. ("the area of either arm that is anterior to (in front of) the bend of the elbow")

8 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. p. 18.("To prevent patient complications and ensure accurate test results: Tourniquet application must not exceed one minute before accessing the vein in order to prevent hemoconcentration. If a tourniquet has been in place for longer than one minute before accessing the vein, it must be released and reapplied after two minutes before the venipuncture is performed.")

9 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. 2.9.4 p. 21. ("Devices must not be preassembled by the collector before the patient is identified.")

10 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. 2.9.5 p. 22.

11 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. 2.9.6 p. 22.

12 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. p. 22.

13 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. p. 22.

14 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. p. 23.

15 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. p. 25.

16 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. 2.9.8 p. 25.; BD Vacutainer® Evacuated Blood Collection System. "Overfilling or under filling of tubes will result in an incorrect blood-to-additive ratio and may lead to incorrect analytic results or poor product performance."

17 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Sec. p. 27. ("Immediately after filling any tube that contains an additive the phlebotomist must mix the blood gently and thoroughly by inverting the tube slowly for the required number of inversions per the manufacturer's instructions. To avoid hemolysis, the blood must not be mixed vigorously.") See, BD Vacutainer® Evacuated Blood Collection System. "For proper additive performance, invert BD SST™ Tubes, and Plus Serum Tubes 5 times. Invert Citrate or CTAD tubes 3-4 times. Invert all other filled additive tubes 8-10 times. Do not shake. Vigorous mixing may cause foaming or hemolysis. Insufficient mixing or delayed mixing in serum tubes may result in delayed clotting and incorrect test results." See also, ANSI/ASB Best Practice Recommendation 156, 1st Ed. 2023, Guidelines for Specimen Collection and Preservation for Forensic Toxicology, AAFS Academy Standards Board is the copyright holder and publisher, Sec. 4.6: "capped tubes should be inverted a minimum of eight times immediately after collection."

18 CLSI, Collection of Diagnostic Venous Blood Specimens. 7th ed. CLSI standard GP41, Ch. 3, p. 33. ("When a cautious and calculated relocation has failed, the tourniquet and needle must be removed, the safety device activated, and pressure applied to the puncture site. Any additional attempts at specimen collection must be started from the beginning of the procedure, preferably at the other arm or another part of the body. The same needle must never be used for additional subsequent punctures. It is not advisable for the same phlebotomist to attempt a venipuncture more than twice. If possible, another qualified person should attempt to collect the specimen, or the physician should be notified.")

About the Author

Richard Wagner

Attorney Profile Defense Lawyer Richard Wagner upholds and defends freedoms and liberties enshrined in our United States and California Constitutions.  “Richard was able to achieve an even better outcome for my case than what we initially thought was possible. I couldn't be more grateful to h...