Understanding DUI Blood Tests in California

Last Updated: February 2026 – Reflects current California DUI blood test guidelines and procedures

Understanding DUI Arrests and Blood Tests in California

Being arrested for DUI in California often triggers immediate questions about blood tests, legal rights, and what happens next. DUI blood testing is governed by strict state guidelines that determine when blood can be drawn, how samples must be handled, and how results may be used in court. This guide explains how DUI blood tests work in California, when police can require a blood draw, how accuracy issues arise, and the legal defenses available when testing procedures are flawed. Updated to reflect current California DUI blood test standards, this resource is designed to help drivers understand their rights and protect their future after an arrest.

Key Takeaway: In California, DUI blood tests must follow strict legal and scientific guidelines, and errors in how blood is drawn, handled, or analyzed may invalidate results and create powerful defenses against DUI charges.

Because DUI blood test evidence often plays a central role in prosecution, early review by an experienced DUI Lawyer Orange County can help identify procedural errors, challenge the reliability of results, and build a strong defense strategy from the outset.

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.

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.

This article reflects current California DUI blood testing procedures and state guidelines in effect as of 2026.

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, prescription medication or illicit drugs.
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 agreed 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 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 or sugar in your blood combines with microorganisms such as Candida albicans, creating ethyl alcohol.

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 allegedly had to drink.

DUI defense attorneys in California who have the right experience, knowledge, and skill in these types of cases can spot 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 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 see if your blood was drawn according to accepted medical practices, consider whether:

• the blood tech performed proper “hand hygiene”⁵
• you were positioned comfortably in a seated or recumbent position.⁶
• your arm was positioned horizontally or slanting slightly downward on a suitable support (armrest, table, etc.)⁷
• with your arm extended to form a straight line from the shoulder to the wrist⁸
• the blood tech gathered and inspected all supplies for defects and applicable expiration dates. NOTE: Devices must not be preassembled before the patient is identified.⁹
• you were stuck in the preferred venipuncture area, the antecubital fossa, which is in front of the bend of the elbow (veins on back of hand are also acceptable)¹⁰
• a single-use tourniquet for no longer than one (1) minute was used¹¹
• the phlebotomist put on new gloves¹²
• the puncture site was properly cleansed¹³
• a nonalcohol-based cleanser was used¹³
• the area was allowed to air dry¹³
• if the vein required repalpation after cleansing, the site must be cleansed again.¹⁴
• your arm or other venipuncture site remained in a downward position to prevent refiux or “backfiow” from the collection tube into the vein¹⁵
• the tourniquet was released as soon as blood flow was established to minimize hemoconcentration¹⁵
• the tube was filled to the maximum stated volume (until the vacuum was exhausted)¹⁶
• after completion of the draw, your blood was properly mixed for the per the manufacturer’s instructions¹⁶
• a clean gauze pad was placed lightly over the venipuncture site¹⁷

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.

Taking action early is critical. Speaking with an experienced DUI Lawyer Orange County can help you understand your legal options, protect your rights, and begin building a strong defense immediately.

Call him today at (714) 721-4423 or fill out an online form to schedule a FREE Consultation.

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^{5 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec. 2.6 Hands Are Cleansed, p. 10; citing Boyce JM, Pittet D. Guideline for hand hygiene in health-care settings. Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force Society for Healthcare Epidemiology of America/Association for Professionals in Infection Control/Infectious Diseases Society of America. MMWR Recomm Rep. 2002;51(RR-16):1-45, quiz CEl-4.; WHO. WHO Guidelines on Hand Hygiene in Health Care. World Health Organization; 2009. Accessed 31 October 2024; https://www.who.int/publications/i/item/9789241597906.}

^{6,7,8 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec. 2.8 Patient is Positioned, p. 10.; Sec. 2.8.1 Seated Position, Patients undergoing a blood draw in a seated position must sit in chairs that have safety features (eg, arm rests or commercial venipuncture chairs) to provide support and prevent falls if the patient loses consciousness. When chairs with safety features are not available, the specimen must be collected with the patient in a recumbent position. 2.8.1.1 Inpatient and Outpatient Facilities, Patient specimens must not be collected while the patient is sitting upright on an examination table, side of a bed, or on any surface without arm rests or other barriers designed to prevent falls.}

^{9 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec. 2.9.1 Supplies Are Gathered, p. 12.}

^{10 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec. 2.9.2 Site Is Selected, p.12.}

^{11 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, 2.9.3 Vein Is Selected; 2.9.3.1 Tourniquet Is Applied p. 14. When used inappropriately, tourniquets pose a risk to patients and can affect test results.}

^{12 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec 2.9.4 Gloves Are Donned, p. 17.}

^{13 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec. 2.9.5 Venipuncture Site Is Cleansed The puncture site must be cleansed to minimize microbiological contamination of the specimen and patient infection. Sec. 2.9.5.1 Cleansing Method for Venipuncture p. 17, If the specimen is being collected for a blood alcohol level analysis, use a nonalcohol-based cleanser. 2. Air dry the area. This practice prevents the patient from experiencing a burning sensation when the venipuncture is performed and enables optimal decontamination. Avoid blowing on the site to expedite drying. NOTE: Studies and articles suggest back-and-forth friction is superior to circular concentric cleansing.}

^{14 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec. 2.9.5.2 Touching the Site After Cleansing. p.17, lf venipuncture proves difficult and the vein requires repalpation after cleansing, the site must be cleansed again. Refer to Subchapter 2.9.3.1 if recleansing results in prolonged tourniquet constriction}

^{15 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec. 2.9.6 Needle Is Inserted and Blood Is Aspirated, 2.9.6.1 Evacuated Tube Method, Sec. 2.9.6.2 Syringe Method In general, p.18, venipuncture using a traditional needle and syringe should be avoided for safety reasons. Sec. 6.4.14 Syringe p. 47. Syringes must be sterile and discarded after use. Sterility of the device should be ensured before use.}

^{16 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec. 2.9. 7 Collection Tubes Are Filled and Mixed, p. 20, All additive tubes must be filled to their stated volumes (see Subchapter 2.9.7.2). Closures must not be removed to fill tubes or transfer blood from one tube to another. To ensure accurate test results, prevent specimen rejection, and achieve optimal blood to additive ratio, blood must fill the tube until the maximum stated volume is reached (ie, vacuum is exhausted). Visually assess the tube to ensure adequate filling. 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.”  When the tube is filled to its stated volume … mix by gentle inversion … Mix the blood gently and thoroughly by inverting the tube slowly for the required number of inversions per the manufacturer’s instructions. … and release the tourniquet before withdrawing the needle from the vein if it was not released. Sec. 2.9.7.3 Mixing Tubes, p. 21, Immediately after filling any tube that contains an additive, the health care professional must mix the blood gently and thoroughly by inverting the tube slowly for the required number of inversions per the manufacturer’s instructions. For multiple tube collections, the blood can be mixed while the next tube is filling. 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.”}

^{CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute, Sec. 6.4.5 Venous Blood Collection Tubes, p.45. Venous blood collection tubes are sterile and manufactured to withdraw a predetermined volume of blood. Instructions furnished in the manufacturer’s package insert of venous blood collection tubes should be available. Blood collection tubes must be stored in accordance with the manufacturer’s recommendations. For information on venous blood collection tubes, refer to CLSI GP39.}

^{17 CLSI, Collection of Diagnostic Venous Blood Specimens. 8th ed. CLSI standard PRE02, Clinical and Laboratory Standards Institute Sec. 2.9.8 Needle Is Removed and Disposed, and Pressure Is Applied, p.22. Cotton and rayon balls are not recommended for applying pressure because of the possibility of dislodging the platelet plug at the venipuncture site.}

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, prescription medication or illicit drugs.
3. The alleged drunk driver has chosen to take the blood test rather than the breath test after being arrested for DUI.