What Is a Blood Split Motion in CA?

In California DUI cases, blood test evidence often plays a major role. When prosecutors claim that a driver was intoxicated, the DUI blood test results are often seen as key evidence against that person. What people don't often realize, however, is that DUI blood samples may not be tested correctly, which can alter the results.

Errors can happen during testing, but they can also happen during blood collection, storage, transportation, or laboratory analysis. Because of this, defense attorneys may file a "blood split motion" when they are defending their client in court for a DUI charge.

A blood split motion allows the defense to request a separate part of the blood sample for independent tests. This can be a very important process when challenging the accuracy or reliability of the prosecution's chemical evidence.

For drivers who are facing DUI charges in Sacramento and asking "what is a blood split motion in CA?" the answer is very important for the case.

What Is a Blood Split?

When law enforcement officers obtain a blood sample in a California DUI case, the sample is usually divided into different portions. One portion is usually tested by the official government crime lab or other approved lab. Another portion is often preserved for testing at a later time.

A blood split motion is a legal request by the defense asking the court to allow access to part of the preserved blood for independent testing. The defense may hire a private lab to examine the blood and determine if the government testing was accurate or not. This type of review can sometimes uncover issues that affect how reliable the prosecution's evidence really is.

Why Blood Tests Matter in DUI Cases

Blood tests are often used in DUI cases, especially those that involve alcohol-related charges, drug-related charges, DUI cases that involve prescription medications, accidents that involve suspected impairment, and felony DUI investigations.

Unlike a breath test, but similar to a urine test, a blood test can measure both alcohol and drugs within the body. Breath samples can only pick up alcohol when a breath testing machine is used.

Prosecutors often rely heavily on urine, blood, or breath test results when trying to prove impairment or unlawful blood alcohol concentration (BAC) levels. In many cases, the results of these tests showing a person's blood alcohol concentration is a central piece of evidence in a case. For more information, our criminal defense law firm in Sacramento CA may be able to help.

Blood Testing for a Driver's Blood Alcohol Concentration Is Not Always Perfect

Many jurors assume that when a blood test is done that the result is 100% accurate. Unfortunately, that's not true. There are actually a number of things that can happen when testing blood when trying to determine blood alcohol content. Some of these issues include:

• Contaminated samples

• Improper storage

• Fermentation inside the sample

• Labeling mistakes

• Broken chain of custody

• Laboratory errors

• Equipment calibration issues

• Improper testing procedures

Even small errors can potentially affect the final report, which shows blood alcohol concentration, and if it's not accurate, it could potentially put an innocent person behind bars or force an innocent person to pay fines that they should not have to pay.

Because of this, if the defense believes the results are inaccurate, they can ask the court to get the blood independently retested at an independent lab. Then, they can compare those results to the initial test.

Why Defense Attorneys File Blood Split Motions

Since splitting DUI blood samples is common practice, many defense attorneys will ask for a blood split motion instead of blindly accepting the initial findings. They are allowed to do this by California law and often do in the following cases:

• To confirm the reported BAC result

• To look for contamination

• To identify improper preservation

• To challenge laboratory procedures

• To evaluate possible fermentation

• To examine chain of custody problems

• To determine whether testing errors occurred

In some situations, independent blood split tests vary significantly from the original test. If the independent test shows a vastly different result than the one from law enforcement testing, it often weakens the prosecution's case.

Fermentation Issues in Blood Samples

Sometimes, a big issue occurs in DUI blood cases: fermentation.

If the blood sample isn't stored correctly, microorganisms might produce alcohol inside of the sample after it's collected. this can increase the alcohol concentration.

Proper preservatives and storage procedures are important to help prevent this issue.

A defense expert who is reviewing the split sample may determine that fermented blood is in the sample, which affected test results.

This becomes very important when the BAC is very close to the legal limit, and it's certainly grounds to fight DUI charges.

Chain of Custody Problems

Chain of custody issues might also affect a blood sample. So, blood evidence is carefully tracked from the moment it is collected...or its supposed to be.

The prosecution must show that the sample was:

• Properly collected

• Properly labeled

• Properly stored

• Properly transported

• Properly analyzed

If there are gaps in the chain of custody, questions might arise about whether the sample was handled correctly, contaminated, or if it got mixed with another person's sample.

Drug DUI Cases and Blood Testing

It's also important to note that blood split motions aren't just limited to DUI cases involving alcohol. They are also important for those who are accused of driving under the influence of marijuana, prescription medications, illegal drugs, or more than one substance.

Drug DUI cases can be very complex because the presence of a substance doesn't automatically prove that the person was impaired when they were driving. Some drugs remain detectable in the blood after the affects have faded.

Timing Can Matter

Blood split motions are often time-sensitive.

Over time, blood samples may degrade or become less reliable for retesting purposes. Because of this, defense attorneys frequently act quickly to preserve the ability to conduct independent analysis.

Waiting too long can create problems if:

• The sample deteriorates

• The sample is destroyed

• Storage conditions change

• Evidence becomes unavailable

Early legal intervention may help protect important defense opportunities. They can help with questions like is california a stand your ground state?

How the Process Works

When a defense attorney seeks independent testing, they may file a motion requesting access to the preserved blood sample.

The court may issue orders allowing the defense expert or laboratory to obtain part of the sample for analysis.

The independent laboratory may then evaluate:

• Blood alcohol concentration

• Presence of drugs

• Preservation methods

• Laboratory procedures

• Sample integrity

The results may later become part of negotiations, motions, or trial testimony.

Can Independent Testing Help Reduce Charges?

In some cases, independent blood testing may help support defenses that lead to:

• Reduced charges

• Dismissals

• Favorable plea negotiations

• Trial defenses

For example, if retesting reveals a lower BAC than originally reported, the prosecution’s case may become weaker.

Likewise, evidence of contamination, fermentation, or procedural violations may raise reasonable doubt.

However, outcomes depend heavily on the facts of the case and the strength of the available evidence.

Blood Split Motions in Felony DUI Cases

Blood evidence often becomes especially important in felony DUI investigations involving:

• Serious injury accidents

• DUI manslaughter allegations

• Repeat DUI offenses

• Cases involving drugs

Because the potential penalties are much more severe, defense attorneys frequently scrutinize blood evidence carefully in these cases.

Independent analysis may become a critical part of the defense strategy.

Prosecutors Often Rely Heavily on Chemical Tests

Many DUI cases heavily depend on the results of chemical tests, including blood tests, urine samples, and breath tests. In fact, jurors often look at blood tests in particular and believe that they are very accurate and scientific proof that the driver was under the influence.

However, lab tests are only as reliable and the procedures used to collect, preserve, and analyze the sample.

A blood split motion gives the defense an opportunity to independently examine whether the testing process was reliable.

Without independent review, problems with the original testing may go undiscovered.

Other Evidence Still Matters

Even when blood test evidence exists, prosecutors may also rely on other forms of evidence, including:

• Officer observations

• Field sobriety tests

• Driving patterns

• Body camera footage

• Witness statements

• Accident evidence

Likewise, the defense may challenge whether the driver actually showed signs of impairment despite the reported chemical test result.

DUI cases often involve multiple layers of evidence and legal issues.

Get a Lawyer for All California DUI Cases

Blood split motions involve both scientific and legal issues that can significantly affect a DUI case. These are complicated, though, and legal assistance can make or break the case.

An experienced DUI defense attorney may help their client in the following ways:

• Request preservation of evidence

• File appropriate motions

• Work with toxicology experts

• Analyze laboratory procedures

• Challenge chemical test results obtained by the prosecutor

• Identify constitutional issues

Because chemical evidence can strongly influence prosecutors and juries, carefully reviewing blood test procedures is often an important part of the defense process.

Those who have been arrested and charged with DUI are not alone. California DUI lawyers are available and willing to help.

If you are facing a DUI charge in California, and you need an attorney to help you through the process, reach out to Goss Law. Free consultations are available, and if necessary, blood split motion help is available.