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Blood Evidence

It is universally assumed that the analysis conducted of an individual's blood is the most reliable means of determining that person's blood alcohol concentration. While the fundamentals of this belief are sound, the actual collection, preservation, and analysis of a blood sample can have profound impacts on the accuracy of the testing.

Once a person is arrested for DUI, the arresting officer should advise them of the right to choose between a blood or breath test. While it is increasingly common for police officers to dissuade arrestees from selecting this form of testing, it is your right to have a blood sample drawn; unless there is no means to safely draw the sample without a significant delay.

Once arrested, a police officer will typically transport the subject to a police station, jail facility, medical clinic, or hospital for the blood draw. California law mandates that the person drawing the blood be appropriately trained and certified, such as a phlebotomist or nurse. The blood is to be drawn in a medically approved manner and the blood draw should be witnessed by the arresting officer. Once the blood is drawn, the technician will either retain custody of the sample themselves, or release the sample to the arresting officer so that it may later be placed into an evidence locker or refrigerator waiting the intervention of the crime lab.

Although California Law mandates that blood samples be drawn in a medically approved manner, there are increasing instances of police agencies, including the California Highway Patrol, who summon blood technicians to the side of the road to have a blood sample drawn. This must bring into the question the reliability of an organic substance being drawn from a human body in an environment rife with gasoline and chemical fumes.

Blood is an organic compound that begins to degrade the instant it departs the human body. In an effort to slow or control the degradation process, evidential test tubes contain a pre-determined amount of anti-coagulant/preservative. The technician drawing the blood sample should shake the vial vigorously to mix the blood with the preservative; otherwise the sample may clot, degrade, or ferment, thereby making analysis of the blood unreliable.

Once the blood is received by the crime lab, a small portion of the blood is extracted from the blood vial. Two separates runs are conducted on the blood sample and then the results are averaged to come to the final blood alcohol concentration.

The DUI team at our criminal defense law firm are experts in evaluating the entire blood testing sequence. We have the experience and training necessary to review the method of blood draw, the method of maintaining the sample and the method of testing.