Blood Split Motions in California DUI Cases

A "blood split" or "blood split motion" occurs when a California DUI DUI defense attorney conducts an independent test of the blood sample that the DUI defendant provided when s/he took a DUI blood test.

When the police take a blood sample in a California DUI arrest, they send a portion of the blood to a crime lab for analysis. But they are also required to save a portion of the blood--and make that portion available to the DUI defendant for retesting in an independent laboratory.1

(It is also possible to do a "urine split" and retest a urine sample for defendants who took a DUI urine test. But there is no such thing as a "breath split" for cases where the defendant took a DUI breath test, since police are not required to retain DUI breath samples.)

We do a blood split in almost every DUI case where the client gave blood. A blood split motion can help with a DUI defense strategy if, for example:

  • The independent laboratory gets a lower blood alcohol content (BAC) reading than the police lab did; or
  • The blood sample was contaminated due to mishandling or faulty collection procedures.

Below, our California DUI defense attorneys answer the following frequently asked questions about California DUI blood splits and blood split motions:

If you have further questions about California blood split motions after reading this article, please feel free to contact us at Shouse Law Group.

1. Are There Rules About How California DUI Blood Tests Are Conducted?

California law establishes numerous rules for how police must conduct DUI blood tests. Finding violations of those rules is one of the major reasons to conduct a DUI blood split.

Anyone arrested for DUI in California is required to take either a blood test, a breath test or a urine test--or else face penalties for chemical test refusal.2

The result of these chemical tests has a strong impact on your DUI case.  If your test result shows a blood alcohol content of 0.08% or higher, it is presumed you were driving under the influence under Vehicle Code 23152(b) VC.3

A blood split motion can help uncover Title 17 violations that can be used to fight your DUI charges.

 And even if you were charged with driving under the influence of drugs where there is no "magic number" to presume intoxication, a blood test result showing the presence of drugs or a high level of drugs would be detrimental to your case.  

This is where a blood split motion can come in handy.

Title 17 of the California Code of Regulations controls how all blood tests in California DUI investigations must be conducted and how the blood samples must be analyzed and stored.

A DUI defense attorney can use the results of an independent blood test following a blood split to challenge any blood test results that do not strictly follow the required steps. The Title 17 regulations that are broken most often include

  • blood samples must be collected as soon as possible after the alleged DUI,4
  • blood samples must be collected by an authorized technician,5
  • enough blood must be collected to allow for re-tests/blood split motions,6
  • the blood must not be contaminated,7
  • the draw site must not be sanitized by an alcohol-based disinfectant,8
  • the blood vial must have sufficient anticoagulant and preservative,9 and
  • the blood must have been sufficiently mixed with the anticoagulant and preservative.10

2. Can My DUI Attorney Request a "Breath Split" If I Took a DUI Breath Test?

Unfortunately, a "blood split motion" is only a viable strategy for DUI defendants who took a blood test or a urine test (see below).

A "blood split motion" equivalent is not available if you took a DUI breath test.

Unlike blood and urine samples, law enforcement agencies are not required to retain breath samples.11 Even when a police officer fails to tell a defendant who chooses a breath test that his or her breath sample will not be retained for retesting, the breath test result can still be used against the defendant at trial.12

So the possibility of a blood split and blood sample retest is one argument in favor of a DUI blood test over a DUI breath test.

3. Can I File a "Blood Split Motion" If I Took a DUI Urine Test?

Yes. DUI urine tests are like DUI blood tests, in that police are required under Title 17 to

  • collect enough of urine so that it may be tested at least twice,13
  • keep the tested sample for up to one year after it is collected,14 and
  • turn over a portion of the urine sample to the DUI defense team upon request (the equivalent of a blood split).15

Title 17 also sets forth required procedures for DUI urine tests. If these procedures were not followed, the equivalent of a "blood split motion" for urine will help your DUI defense attorney discover and prove this. Urine test requirements include:

  • the urine sample cannot be collected any sooner than 20 minutes after the defendant first urinates after the arrest,16
  • the container must not be contaminated,17 and
  • the container must have sufficient preservative.18

4. How Do I Make a California Blood Split Motion?

A "blood split" motion usually begins with the defendant's DUI defense lawyer informally asking the prosecutor to turn over the blood or urine sample, and the prosecutor agreeing to do so. (California criminal law requires prosecutors to disclose all evidence obtained in a criminal investigation to defendants, including DUI defendants.)19 

In most cases, prosecutors will respond to a blood split motion by turning over the remaining blood sample.

If the prosecutor refuses or fails to turn over the blood split (or urine split) sample within fifteen (15) days, the court will become involved and order the prosecutor to do so.20

In addition to compelling the prosecutor to turn over the blood split, the court may discipline the prosecutor. This discipline may include contempt proceedings, informing the jury of the delay, or even preventing the prosecutor from using the original blood or urine test result at trial.21

Your right to obtain a blood split or urine split is also protected under the California Vehicle Code and Title 17. However, if you fail to conduct additional tests on your blood split sample or are unable to do so, this will not prevent the prosecutor from using the original result against you unless s/he acted in bad faith.22

5. How Can a Blood Split Motion Help Me Fight California DUI Charges?

An experienced DUI attorney can use a blood split motion to discover and make several California DUI defenses. These include:

You had a BAC below 0.08% at the time you were driving

Example:  Brad has a few drinks with his friends in downtown Barstow. While he is driving home, he is arrested for DUI. The officer asks him which chemical test he would like, and Brad chooses a blood test. The Barstow Police Department technician determines his BAC to be 0.09%.

But Brad's DUI defense attorney requests a blood split and conducts an independent retest. He discovers that Brad's BAC was actually 0.07% and that the police technician made a mistake. Brad's lawyer then uses this evidence to persuade the prosecutor to dismiss the charge. 

Your blood or urine sample did not contain enough anticoagulant or preservative

Example: Emily meets up with some co-workers after work for margaritas at a bar. On the way home, she is pulled over by a California Highway Patrol officer and arrested for DUI. She requests a blood test, which shows her BAC to be 0.10%.

Emily's DUI attorney requests a blood split. The independent blood test reveals that the blood vial had insufficient anticoagulant or preservative, which caused the blood to ferment and give a falsely high BAC. 
A blood sample insufficiently mixed with preservative or anticoagulant can help your DUI defense.

Your blood or urine sample was not sufficiently mixed with preservatives or anticoagulant

Example: Jason goes to a barbecue at a friend's house in Victorville and has a few beers. On his way home, he is pulled over and arrested for a DUI. He requests a blood test.

Jason's Victorville DUI attorney requests a blood split and has the sample retested.

The independent laboratory discovers that the police technician didn't sufficiently shake the blood vial to mix the blood with the anticoagulant and preservative. So the blood had fermented and when it was tested, it gave a falsely high BAC.

The DUI lawyer uses this information at Jason's jury trial to attack the prosecution's evidence.

Your blood or urine sample was contaminated

Example: Christine is on a coed softball team in Pasadena that just won the championships. She goes out for a few drinks to celebrate with the team, but on her way home, she's pulled over and arrested for a DUI.

Christine's experienced Pasadena DUI attorney makes a blood split motion.

After having the blood sample retested, her attorney discovers that the blood was contaminated. The police technician who drew the blood had improperly cleaned the draw site with an alcohol-based cleaner, resulting in a higher BAC.  

Christine's lawyer uses this information to negotiate a DUI plea bargain to a minor traffic charge.

Your blood or urine sample was lost or destroyed by the police laboratory

Example: Hannah attends a concert in downtown Los Angeles with some friends. While there, she takes some ecstasy. On her way home to Beverly Hills, she is pulled over and arrested for DUI of drugs. She is asked to provide a urine sample.

Hannah's Beverly Hills DUID attorney requests a portion of the urine sample (a "blood split motion" for urine), but discovers the sample has been lost. At trial, Hannah's lawyer argues that the prosecution doesn't even have the urine sample to admit into evidence and throws suspicion on the original urine test.

Your blood or urine sample was switched with someone else's

Example: After being arrested for a DUI in Oxnard, Miguel submits to a blood test. After the test, he is told he had a BAC of .10%. However, he knows that he only had one drink that night.

Miguel's Ventura County DUI lawyer requests a blood split and has the blood sample retested. The new result shows Miguel's blood to have a BAC of .04%, well below the legal limit.

It turns out there had been a clerical error and the technician had tested the wrong blood sample, thinking it was Miguel's. Miguel's DUI defense attorney easily persuades the prosecutor to drop the charges.

6. Can a Blood Split Hurt My California DUI Defense?

Sometimes a blood split will return results that are not beneficial for the defendant.  For instance, the independent testing may confirm the accuracy of the originally reported BAC--or even show a higher BAC than the law enforcement technician reported.  

However, independent review of blood or urine samples through a blood split order is the defendant's evidence. If the defendant does not plan to use the results at trial, he or she is not required to disclose it to the prosecution.23

In other words, it might turn out to be the case that a blood split motion does not help your California DUI defense. But it can't actually hurt it either.

Call us for help . . . 


If you or a loved one is in need of help with blood split motions in a California DUI case, we invite you to contact us at Shouse Law Group.

We have local offices in Los Angeles, the San Fernando Valley, Pasadena, Long Beach, Orange County, Ventura, San Bernardino, Rancho Cucamonga, Riverside, San Diego, Sacramento, Oakland, San Francisco, San Jose and throughout California.

Legal References:

  1. Vehicle Code 23158(b) VC -- Right of DUI defendant to make a blood split motion. ("(b) The person tested may, at his or her own expense, have a licensed physician and surgeon, registered nurse, licensed vocational nurse, duly licensed clinical laboratory scientist or clinical laboratory bioanalyst, person who has been issued a "certified phlebotomy technician" certificate pursuant to Section 1246 of the Business and Professions Code, unlicensed laboratory personnel regulated pursuant to Sections 1242, 1242.5, and 1246 of the Business and Professions Code, or any other person of his or her own choosing administer a test in addition to any test administered at the direction of a peace officer for the purpose of determining the amount of alcohol in the person's blood at the time alleged as shown by chemical analysis of his or her blood, breath, or urine. The failure or inability to obtain an additional test by a person does not preclude the admissibility in evidence of the test taken at the direction of a peace officer.")
  2. Vehicle Code § 23612 VC -- Requirement that a person arrested for DUI take blood, urine or breath test.
  3. Same.
  4. 7 California Code of Regulations ("CCR") § 1219.1(a). ("Blood samples shall be collected by venipuncture from living individuals as soon as feasible after an alleged offense and only by persons authorized by Section 13354 of the Vehicle Code.")
  5. Same; Vehicle Code 23158(a) VC. 
  6. 7 CCR § 1219.1(b).
  7. 7 CCR § 1219.1(c) [no use of alcoholic disinfectant]; Id. § 1219.1(d) [must use sterile needles or syringes or clean containers]; Id. § 1219.1(d) [blood sample must be kept in a clean, dry, and closed container].
  8. 7 CCR § 1219.1(c).
  9. 7 CCR § 1219.1(e)(2) ("The blood shall be mixed with an anticoagulant and a preservative.").
  10. Same.
  11. California v. Trombetta (1984) 467 U.S. 479 (holding the failure to retain breath samples, which makes the equivalent of a blood split unavailable for breath samples, does not violate a defendant's constitutional due process rights).
  12. People v. Mills (1985) 164 Cal.App.3d 652; In re Garinger 188 Cal.App.3d 1149.
  13. 7 CCR § 1219.1(b). ("Sufficient blood shall be collected to permit duplicate determinations [i.e., blood splits].").  Section 1219.2 does not explicitly state that a sufficient amount of urine must be retained for retesting, but it can be inferred from the rest of the statute.
  14. 7 CCR § 1219.1(g)(2) ("Whenever a [blood] sample is requested by the defendant for analysis [through a blood split motion] and a sufficient sample remains, the forensic alcohol laboratory or law enforcement agency in possession of the original sample shall continue such possession, but shall provide the defendant with a portion of the remaining sample in a clean container together with a copy or transcript of the identifying information carried on the original sample container."); 7 CCR § 1219.2(c)(1) ("Whenever a [urine] sample is requested by the defendant for analysis [through a blood split motion] and a sufficient sample remains, the forensic alcohol laboratory or law enforcement agency in possession of the original sample shall continue such possession, but shall provide the defendant with a portion of the remaining sample in a clean container together with a copy or transcript of the identifying information carried on the original sample container.")
  15. 7 CCR § 1219.1(g) ("In order to allow for analysis by the defendant [blood split], the remaining portion of the [blood] sample shall be retained for one year after the date of collection."); 7 CCR § 1219.2(c) ("In order to allow for analysis by the defendant, the remaining portion of the [urine] sample shall be retained for one year after the date of collection.")
  16. 7 CCR § 1219.2(a). ("The only approved urine sample shall be a sample collected no sooner than twenty minutes after first voiding the bladder.")
  17. 7 CCR § 1219.2(b). ("The specimen shall be deposited in a clean, dry container which also contains preservative.")
  18. Same.
  19. Penal Code 1054.1(c) PC -- Procedures for defense to request evidence disclosure from prosecutor, including for a blood split motion; Penal Code 1054.5(b) PC.
  20. Penal Code 1054.5(b) PC -- Requirement that prosecutors turn over relevant evidence, including in response to a blood split motion.
  21. Same.
  22. Vehicle Code 23158(b) VC -- Right to blood split; 7 CCR §§ 1219.1(g)(2), 1219.2(c)(1).
  23. Penal Code 1054.3(a) PC -- Disclosure requirements for defendants; does not extend to re-tested blood split samples that will not be presented at trial.


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