How Accurate Are DUI Blood Tests?

California law recognizes 2 different types of DUI: “pro se” and “under the influence.” A pro se DUI charge is solely based on your blood alcohol content (BAC), as calculated by a chemical test. An “under the influence” DUI occurs when your driving is impaired as a result of alcohol or drug use. In either case, the court may use the results of a chemical test, such as a blood test, as evidence against you.

How accurate are blood tests compared to breath tests, and what are some of the defenses you can use to fight the results? Keep reading to find out.

Breathalyzer vs. Blood Test

Breathalyzers, or devices that identify your level of impairment based on the alcohol content of your breath, can provide a relatively accurate BAC measurement if regularly cleaned and calibrated. Regular maintenance is essential, as these devices are known to produce inaccurate readings from other, nonalcoholic substances, such as mouthwash, or from leftover alcohol residue in your mouth.

Blood tests determine your actual blood alcohol content using a chemical analysis. Authorities collect a sample of your blood during the arrest, and a laboratory chemist analyzes your blood at a later date. Unlike breath tests, blood tests determine the exact BAC level at the moment of extraction. Blood tests do not produce false positives, nor do they indicate a higher BAC as a result of poor calibration. Therefore, blood tests are generally more accurate indicators of BAC compared to breathalyzers.

Ways to Fight Blood Sample Tests

Depending on the lab, your blood sample may take up to a week to test, which creates an opportunity for errors to occur. These errors can be used as defenses against blood tests and may help you fight a DUI charge.

Rising BAC Factors

Your body absorbs alcohol over a period of time. Depending on your gender, weight, how much food you’ve consumed, and how long you’ve been drinking, it can take up to 2 hours to reach your peak BAC level. It is not illegal to have a high BAC. It is only illegal to drive with a BAC of .08% or greater.

Therefore, if authorities collect your blood after your initial arrest, the test may not yield an accurate result of your BAC while you were driving, and you may not be guilty of DUI.

Retesting the Sample

A chemical test only requires the use of half of the collected blood sample. State law requires technicians to save the other portion for at least a year. Your attorney can request to have this portion tested by an independent lab. If an independent test produces different lab results from the initial analysis, your attorney may argue that an error occurred during the initial process, leading to inaccurate results.

The most common errors that occur during chemical tests include:

  • Blood fermentation
  • Contamination
  • Mistaking someone else’s blood sample for yours

If the court agrees that the initial lab results are inaccurate, you can potentially have them thrown out entirely. If your charges are pro se, the court may not have the evidence to pursue the case and may be forced to drop your charges.

Title 17 Violations

California law regulates the standards for proper administration and preparation of chemical tests. Known as Title 17, these regulations protect your rights as a defendant. Should anyone violate these regulations, you can claim that the evidence is no longer valid.

Some of the most common violations for blood tests include:

  • Lack of preservative in the blood sample: Authorities must add a preservative to your sample at the time of extraction to prevent the blood from fermenting. If not enough preservative is added, the resulting fermentation can falsely increase the reported BAC level.
  • Lack of anticoagulant (anti-clotting agent) in the blood sample: Blood clots over time. To prevent the blood from clotting, authorities add an anticoagulant to the sample. If not enough is added, the sample’s chemical composition may change prior to testing and affect the results.
  • Lack of proper storage: If laboratory staff does not store the sample in the correct, mandated conditions, or does not keep the sample for a full year, they are violating Title 17 protocols.
  • Expired anticoagulant or preservative: If authorities add expired preservative or anticoagulant to the sample, the additives may not be effective, and the sample may be compromised.

Your attorney can use any of the above violations as an argument to throw out the test entirely. If the court throws out the results, they may no longer have enough evidence to convict you of a DUI.

Contact Our Fresno DUI Attorney Today To Discuss Your Charges – (559) 484-2112.

When it comes to your rights, no one fights for you like our Fresno DUI lawyer, Brian C. Andritch. He takes the time to learn the details of your case, examine every piece of evidence, and build a solid defense to get you a beneficial outcome. The Law Office of Brian C. Andritch is available 24 hours a day and has helped thousands of clients.

Schedule a free consultation with Attorney Brian C. Andritch today: (559) 484-2112.

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