A drunk driving charge in Florida is comprised of two different elements – driving while impaired, and violating the state’s ‘per se’ laws, which is another way of saying that the driver’s blood alcohol content (BAC) was .08 percent or greater.  The per se allegation is separate from the accusation that a driver was mentally or physically impaired behind the wheel, or driving under the influence. A prosecutor needs to prove only one of the two elements to convict a motorist of drunk driving.

Prosecutors typically rely on a driver’s chemical test results to prove the per se element of a drunk driving case. Many motorists fear that a blood, breath or urine test that showed .08 percent BAC or higher means that their case is doomed. But chemical test results are not infallible. An experienced Florida DUI / DWI attorney will effectively challenge chemical test results as part of a strategy to help accused drunk drivers to win their cases.

Chemical tests used in DUI / DWI cases have a huge potential for error. Breath testing machines don’t take the temperature of a person’s breath, even though higher breath temperatures can inflate BAC readings. The biggest problem breath testing machines is that they are calibrated to test an “average” person. We all know there is no such thing as an average person – people come in all shapes and sizes, and individuals metabolize alcohol at all different rates.

Blood tests can be equally unreliable. The integrity of a blood sample can be compromised by improper collection, storage, and analysis. Blood should always be drawn into a tube with white powder in the bottom – the powder is a preservative and anti-coagulant – but the powder-filled tubes come from a factory somewhere, and are never checked. And 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.

The timing of chemical testing is instrumental in launching an effective defense challenge. In many cases, the driver’s blood alcohol content (BAC) is tested hours after the driver was last behind the wheel of a car. It’s important to keep in mind that it’s not against the law to have a BAC of .08 or .14 at the police station, where the test is given – only when driving. However, many prosecutors use the results of chemical tests taken hours after a motorist was last behind the wheel to try to convict drivers of violating Florida’s per se laws.

It’s quite possible that a driver whose BAC was above the legal limit at the police station may have been below the legal limit when driving. The complex process of absorption and elimination of alcohol in the human body causes a person’s BAC to rise long after he or she takes that last drink.