A DUI blood test result can be one of the most important pieces of evidence in a California driving under the influence case. When prosecutors allege that a driver was impaired by alcohol, the reported blood alcohol concentration (BAC) may play a major role in determining how the case proceeds.
However, a blood test result is not automatically beyond question. Like all evidence used in court, DUI blood evidence must be collected, handled, analyzed, and presented according to proper legal and scientific procedures.
One tool available in many California DUI cases is a blood split motion. This process allows the defense to seek access to a portion of the blood sample so it can be independently analyzed. The purpose is not to assume that the original test was inaccurate, but to allow an independent review of evidence that may significantly affect the outcome of a criminal case.
What Is a Blood Split Motion in a California DUI Case?
A blood split motion is a request for access to a DUI blood sample so that an independent laboratory can conduct additional testing.
When law enforcement obtains a blood sample during a DUI investigation, the sample is typically collected into multiple vials. One vial may be tested by a government laboratory, while another portion may remain available for additional examination.
Through a blood split motion, the defense may seek permission to have the preserved sample tested independently.
For example:
A police laboratory reports that a driver’s BAC was 0.09%. The defense requests independent testing of the remaining blood sample. The second test produces a significantly different result. That difference may raise questions about the original testing process, laboratory procedures, or the reliability of the reported BAC.
A blood split motion does not automatically invalidate a DUI blood test. Instead, it gives the defense an opportunity to evaluate whether the evidence is scientifically reliable.
Why Are Blood Split Motions Important in California DUI Cases?
California DUI prosecutions often rely heavily on chemical evidence. Under California law, a person charged with DUI may face allegations based on either impairment or a BAC level that violates the legal limit.
For alcohol-related DUI cases, prosecutors frequently rely on blood, breath, or urine testing to establish the alleged BAC. However, scientific evidence must still meet legal standards before it can be relied upon in court.
A blood split motion allows the defense to investigate important questions, including:
- Was the blood sample properly collected?
- Was the sample stored correctly?
- Was the chain of custody properly maintained?
- Did the laboratory follow accepted testing procedures?
- Was the equipment properly maintained and calibrated?
- Were there possible testing errors?
- Does independent analysis support or contradict the original result?
The goal is to make sure that DUI evidence is evaluated carefully and accurately.
How Does the California DUI Blood Split Process Work?
The process can vary depending on the circumstances of the case, but it generally involves several steps.
1. Reviewing Available Evidence
The defense typically reviews information such as:
- Police reports
- Laboratory reports
- Blood collection records
- Discovery materials provided by the prosecution
- Documentation regarding handling and storage of the sample
This review helps determine whether independent testing may be appropriate.
2. Filing a Motion or Request for Independent Testing
A DUI defense attorney may file a formal request with the court seeking access to the remaining blood sample. California criminal defendants have discovery rights that allow them to obtain and inspect evidence relevant to their defense. These discovery obligations are governed in part by California Penal Code section 1054.1.
3. Independent Laboratory Testing
If access is granted and sufficient sample remains available, the blood may be sent to an independent laboratory for analysis.
The independent laboratory may examine whether the reported BAC result is consistent with its own testing.
4. Evaluating the Results
The results of independent testing may provide additional information about the reliability of the original blood test.
The outcome can vary:
- The independent test may confirm the original result.
- It may produce a different result.
- It may identify potential concerns regarding testing procedures.
The significance depends on the specific facts of the case.
Can a DUI Blood Test Be Challenged in California?
Yes. DUI blood evidence can potentially be challenged in several ways.
A challenge does not necessarily mean the blood test will be excluded. Instead, the defense may examine whether the evidence is reliable and whether legal requirements were followed.
Common areas of challenge include:
1. Improper Blood Collection Procedures
California has regulations governing the collection and handling of DUI blood samples. These requirements are designed to preserve the integrity of the sample.
Issues may arise if:
- Proper collection procedures were not followed
- The sample was contaminated
- Required preservatives were not properly used
- Collection records are incomplete
2. Problems With Chain of Custody
The prosecution generally must establish that the blood sample tested in the laboratory is the same sample collected from the defendant and that it was properly handled.
Questions may arise if:
- Documentation is incomplete
- The sample changed hands without proper records
- Storage procedures are unclear
3. Laboratory Testing Errors
Blood alcohol testing requires careful scientific procedures.
Potential concerns may involve:
- Equipment problems
- Calibration issues
- Human error
- Incorrect testing procedures
- Problems with laboratory quality control
Independent testing can sometimes help identify these concerns.
4. Inaccurate BAC Interpretation
Even if a laboratory result is accurate, questions may exist regarding how that result relates to the time of driving.
For example, a blood test performed after a traffic stop may reflect a BAC level at the time of testing, not necessarily the exact BAC at the moment the person was driving.
Factors such as alcohol absorption and elimination may become relevant depending on the circumstances.
Can a Blood Split Motion Get DUI Blood Evidence Thrown Out?
A blood split motion by itself does not automatically exclude a DUI blood test from evidence.
Instead, it provides a method for investigating the accuracy and reliability of the evidence.
If independent testing or further investigation reveals significant problems, the defense may raise those issues through appropriate legal procedures. Depending on the circumstances, challenges may involve:
- Requests to exclude unreliable evidence
- Motions regarding admissibility
- Cross-examination of laboratory witnesses
- Arguments concerning the reliability of scientific testing
Whether evidence is excluded depends on the specific facts and applicable law.
What Happens If the DUI Blood Sample Is No Longer Available?
A blood split motion depends on whether sufficient sample remains available for testing.
If a sample has been consumed, destroyed, contaminated, or is otherwise unavailable, additional legal questions may arise.
The significance of an unavailable sample depends on factors such as:
- Why the sample is unavailable
- Whether proper preservation procedures were followed
- Whether the defense had an opportunity to request testing
- Whether other evidence exists in the case
These issues are evaluated based on the circumstances of each case.
How Accurate Are DUI Blood Tests in California?
Blood testing is generally considered a reliable method of measuring alcohol concentration, but reliability depends on proper procedures being followed.
A reliable DUI blood test requires:
- Proper collection
- Proper preservation
- Qualified laboratory personnel
- Accurate equipment
- Appropriate testing methods
- Proper documentation
Because multiple steps are involved, errors can occur. That is why DUI blood evidence may be reviewed and challenged when appropriate.
Frequently Asked Questions
How soon should a defendant request a blood split motion?
Timing can be important because blood samples are limited and may not remain available indefinitely. The appropriate timing depends on the circumstances of the case and the availability of the sample.
Can I personally request my DUI blood sample for testing?
A defendant generally seeks access to evidence through legal procedures. The process often involves a formal request or motion handled through the court.
Does a different independent test result mean my DUI case will be dismissed?
Not necessarily. A different result may raise important questions, but the impact depends on the overall evidence and legal issues involved.
Can police blood test results be wrong?
Blood testing is generally reliable when proper procedures are followed, but mistakes involving collection, handling, storage, or laboratory analysis can affect accuracy.
Is a blood split motion used only in DUI cases?
Blood split motions are especially common in DUI cases because chemical testing often plays an important role in proving alcohol-related charges.
What other DUI evidence can be challenged besides blood tests?
Depending on the facts, DUI cases may involve challenges involving traffic stops, field sobriety tests, breath testing procedures, police observations, and other evidence.
Why Reviewing DUI Blood Evidence Matters
A DUI blood test result can have serious consequences, but it is not the only factor considered in a case. The accuracy and reliability of scientific evidence depend on following proper procedures at every stage—from collection to laboratory analysis.
A blood split motion provides a way for the defense to independently examine important evidence and determine whether the reported results should be questioned.
Understanding these procedures can help people better understand the legal process after a California DUI arrest and why reviewing the details of a blood test may be important.
Challenging DUI Blood Evidence Through Independent Testing
California DUI blood test results can be powerful evidence, but they must still be evaluated carefully. A blood split motion allows a defendant to seek independent analysis of a blood sample and investigate whether the original testing process produced reliable results.
Every DUI case involves different facts, including the circumstances of the traffic stop, the blood collection process, laboratory procedures, and the available evidence. Anyone facing DUI charges should speak with a qualified legal professional who can review the specific details of the situation.
Contact Southwest Legal
If you have questions about California DUI blood split motions, blood test evidence, or the legal issues surrounding DUI chemical testing, Southwest Legal can provide guidance and help you better understand the legal process. Contact us today for a free consultation to discuss the circumstances of your DUI case with an experienced legal team.
Disclaimer: This article is for general informational purposes only and does not constitute legal advice or create an attorney-client relationship. No attorney-client relationship is formed unless and until the firm and client enter into an agreement for legal services. Laws may change, and legal outcomes depend on the specific facts of each case. Consult a qualified attorney for advice regarding your situation.