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Violation of the Per Se Law

California DUI arrests typically result in two different charges - violating the state's "per se" laws (California Vehicle Code Section 23152 - Driving Under Influence of Alcohol or Drugs), and driving under the influence. "Per Se" is just another way of saying that someone arrested for drunk driving is accused of having a blood alcohol content (BAC) of .08 percent or greater. It's separate from the accusation that a driver was mentally or physically impaired behind the wheel, or driving under the influence.

Most California drivers accused of driving under the influence (DUI), or driving while intoxicated (DWI) worry that a breath or blood test reading of .08 percent or greater means an automatic conviction. But a skilled San Francisco DUI defense lawyer, especially one who has advanced training in field sobriety testing, can challenge the results of both tests.

Chemical testing to determine blood or breath alcohol content take place hours after the driver was last behind the wheel of a car. Keep in mind that it's not against the law to have a BAC of .08 hours later at the police station, where the test is given, but many prosecutors employ that information to convict suspected drunk drivers of violating California's per se laws.

A driver whose blood alcohol content (BAC) exceeded the legal limit hours after driving may have been below the legal limit while behind the wheel. The complicated process of absorption and elimination of alcohol in the human body often causes a person's BAC to rise long after he or she takes that last drink, and that can affect a driver's chemical test.

Information about a suspected DUI driver's BAC comes from two sources - breath tests and blood tests. Both have a huge potential for error. Breath tests are conducted both during traffic stops and at the police station. Roadside breath tests have the biggest potential for error - the handheld machines have no way of detecting mouth alcohol, which can substantially elevate the reading on a breath test. Mouth alcohol is especially prevalent in people who have recently been drinking.

Police station breath testers aren't much better. They don't calculate the temperature of a driver's breath, even though higher breath temperature can escalate a BAC reading. The biggest problem with both types of breath tester - the portable machines and the ones found in the police station - is that they are calibrated to test an "average" person. Anyone who looks around can see that there is no such thing as an average person - people come in all shapes and sizes, with different rates of metabolism.

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Attorneys for the firm represent clients accused of driving under the influence of alcohol or driving with a blood alcohol level at or above the legal limit in San Francisco, San Mateo, Marin, Alameda, Santa Clara, Contra Costa, Sonoma and Napa counties.

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Blood tests can be just as inaccurate as breath tests. A blood sample can be compromised in many ways. Determining whether proper procedures were used when drawing blood can often determine the sample's integrity. Blood should always be drawn into a tube with white powder in the bottom - the powder is a preservative and anticoagulant. Also, in real life, forensic labs don't work the way they do on TV. Often there's a delay of days or weeks before the blood gets tested, and mix-ups are more common than most people believe. There have been documented cases of blood samples with different blood types than the individuals from whom they were supposedly drawn.

There are several effective ways to challenge evidence in a "per se" law of a California DUI Case. The best way to fight a per se drunk driving case is to consult with an experienced California criminal defense lawyer skilled in driving under the influence defense.

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