Drivers arrested for DUI / DWI in Florida must submit to a chemical test to determine blood alcohol content (BAC). Many drivers fear that a blood test result that shows a BAC of .08 percent – the legal limit in all 50 states – means a slam-dunk conviction. However, blood tests, like other chemical tests, can be successfully challenged. A Florida attorney who focuses on defending DUI / DWI cases will work to discredit a blood test result as part of a comprehensive defense strategy.

Everyone who drives in Florida does so under the state’s implied consent law, which means that the driver agrees to take a chemical test if lawfully arrested for driving under the influence of alcohol or drugs.

Some drivers believe that refusing a chemical test is in their best interests, but most reputable defense attorneys advise motorists to agree to the test. Individuals who refuse to submit to a chemical test face severe consequences, including a separate misdemeanor charge if the driver has a previous refusal, and a one-year DMV suspension of the driver’s license for a first refusal. 

There are several challenges available in a DUI / DWI case involving a blood test.  One effective challenge involves questioning the way in which the test was conducted. The technicians who draw and analyze the blood are fallible, and human error is not uncommon. 

In some cases, the technician who draws the blood uses improper techniques. Blood must be drawn into a glass tube with a specific mix of white powder in the bottom – the white powder is a mixture of anticoagulant and preservative. If the powder in the tube does not contain the right amount of anticoagulant, the blood will clot, reflecting an artificially high BAC. If there are improper levels of preservative in the sample, the blood sample can actually ferment, creating alcohol. Testing by a defense pathologist can reveal these kinds of errors. 

Only individuals with the proper certification should draw the blood, and the driver’s arm must be cleaned with an alcohol-free wipe. The sample should be shaken to thoroughly distribute the anti-coagulant and preservative.  The blood sample must be stored in a controlled environment in order to preserve its quality. One essential step in a DUI / DWI defense involving a blood sample is to establish a “chain of custody” in order to fully understand who had access to the sample, and how it was stored. 

It’s also important to note that although a blood test may accurately determine BAC at the time of testing, it doesn’t conclusively prove BAC at the time of driving.  Alcohol levels fluctuate over time, and the crime is driving under the influence, not having a BAC above the legal limit hours after being behind the wheel.