Many DUI clients come to us with one overriding concern about their case. They took the State's blood test, which allegedly shows a blood alcohol content above the legal limit of .08 for DUI in Georgia. They often fear that the odds of overcoming this evidence are too great, even if they do not feel the results are accurate.
It can seem, on it's face, like very damning evidence when facing a DUI. The simple fact is blood tests results alone are not enough to secure a conviction for DUI. There are numerous reasons this is true.
First of all, the State must establish probable cause for the arrest. Law enforcement cannot request a blood draw until they have placed a DUI suspect under arrest. To do so they much establish probable cause to believe that you are committing the offense of DUI. If they fail to do so, the blood test and any other evidence taken or obtained from you after your arrest is inadmissible.
Secondly, the State must show the proper chain of custody for the blood evidence to prove that the blood which was tested is the blood which was taken from you. The blood sample can change hands numerous times between the time it was drawn and the time it was tested or winds up as part of the State's evidence at a DUI trial. If a proper chain of custody is not established the State cannot prove from whom the blood sample was drawn in the first place.
The State also must show that the blood sample was properly stored and not contaminated in any way. Contamination can even occur before the blood is drawn, if the site of the blood draw is not properly sterilized. There are even issues with the method of testing the State uses to determine BAC in a blood test which can cause grave doubt as to the accuracy of any test result.
The bottom line is even with a blood test which purports to show a blood alcohol level over .08 the State has a long way to go to prove DUI.