When a driver is arrested on suspicion of drinking and driving, police conduct a breath or blood test to determine the motorist’s blood alcohol content (BAC) to determine whether it’s over the legal limit – now .08 percent in all 50 states. Although police and prosecutors consider blood tests to be potent evidence in a drunk driving case, they are far from foolproof. It’s imperative to consult with a California attorney who specializes in defending drunk driving cases to learn how blood test results can be challenged.
Once an arrest is made, the driver must submit to chemical testing under a provision in the California Vehicle Code. California’s implied consent law means that anyone licensed to drive in the state consents to taking either a blood or breath test if arrested on suspicion of drinking and driving. If a driver is suspected of driving under the influence of drugs (DUID), a blood or urine test may be required.
If a person fails to submit to the required chemical testing, a number of serious repercussions follow, including fines, mandatory imprisonment if the person is convicted of DUI, and DMV suspension of the person’s driver’s license. Even if a person refuses to take a chemical test, courts have given leeway to arresting agencies to take the defendant’s blood by force. Therefore, submitting to the chemical test is in the best interests of someone arrested for DUI.
Even when a driver takes a breath test, the officer must advise the person of the right to take a blood test in order to retain a sample of blood for later testing by an independent forensic toxicologist. This is a safeguard for the DUI defendant. Tests are fallible, and human error is not uncommon.
One common error in BAC blood testing is improper blood drawing procedures. In a BAC test, blood should be drawn into a glass tube that contains a white powder in the bottom – the white powder is a mixture of preservative and anticoagulant. If there are improper levels of preservative in the sample, the blood sample can actually ferment, creating alcohol. If the sample does not contain enough anticoagulant, the blood will clot, reflecting an artificially high blood alcohol level. Independent testing will reveal such instances. Thus, it is to the DUI defendant’s best advantage to have his or her blood sample independently tested.
In addition to proper use of preservative and anticoagulants, the blood must be drawn by a person certified to perform the draw. The driver’s arm must be wiped with an alcohol-free wipe. Once drawn, the blood sample must be shaken in order to thoroughly distribute the anti-coagulant and preservative. The sample must be kept in a controlled environment in order to preserve the quality of the sample. Therefore, it is beneficial in pursuing a DUI defense to identify the “chain of custody” in order to fully understand who had access to the sample, and how it was stored.
Even if a blood sample was properly drawn and stored, it’s important to note that while chemical testing may be accurate to determine blood or breath alcohol content (BAC) at the time of testing, it is not conclusive evidence of BAC at the time of driving. It is not illegal to be above the legal limit while in a police station; the crime is driving under the influence, or driving above the legal limit, not having a BAC above the legal limit at a later time. Because alcohol levels change over time, this is a critical point to understand.
Ultimately, blood test results can be successfully challenged. When it comes to issues of blood testing in a drinking and driving case, it’s important to have a California lawyer who specializes in DUI / DWI defense on your side.