When a person is arrested for driving under the influence (DUI), the police will conduct either a breath or blood test in order to determine the driver’s blood-alcohol content (BAC) level and whether or not the driver is over California’s .08% limit. Although many consider blood tests to be highly accurate, they are not foolproof. It is always important for California DUI defense attorneys to examine blood test results in order to determine if there was a margin of error that occurred that could possibly indicate that their client’s true BAC was actually lower. Both District Attorneys and toxicologists are unable to state with any certainty that an individual’s actual BAC was above or below a particular level. Toxicologists will concede that there is a variance of 3 to 10 percent within which one’s actual BAC would likely fall. This means that if an individual’s BAC is tested at .08%, it could actually have been .05% at the time the individual was driving.

Additionally, errors often occur during blood test administration. For instance, one common error occurs when blood drawing procedures are not being followed properly. In a blood test, the blood should be drawn into a glass tube that contains a mixture of a preservative and an anticoagulant. If there are improper levels of either of these, then the blood sample could actually ferment, creating alcohol or a clot, resulting in an artificially higher BAC result. Therefore, it is important that any DUI suspect who submits to a blood test administered by the police request an additional draw to be tested later by an independent testing facility.

Furthermore, blood draws must be conducted by an individual who is certified to perform them, and the sample must be kept in a controlled refrigerated environment in order to preserve it. Preservation is a critical factor because otherwise, fermentation can occur. ( California DUI attorneys have uncovered some jurisdictions that do not regularly refrigerate stored samples immediately after a blood draw.) Even if a blood sample is drawn and stored properly, it is important to keep in mind that these tests are not conclusive evidence of one’s BAC at the time he or she was “driving.” Because alcohol levels in the body change over time, this is a crucial point to understand.

It is important to note that even if a DUI suspect refuses to take a chemical test, California courts have given leeway to arresting police officers to conduct forced “blood draws.”

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