Being arrested is a painful and traumatic experience. The foundation of the prosecutor’s case against you in court will rest on the accuracy of the breath or blood tests taken from you at the time of arrest. Although the relative accuracy of these tests has dramatically increased over the years as technology has soared, they certainly are subject to errors which can produce erroneous results.
The accuracy of a blood test should always be carefully evaluated by your attorney, to determine whether or not the result that was produced properly. Without scrutiny, the results of a blood test contained in an arrest report can result in a conviction based upon inaccurate evidence.
Client’s frequently ask after being arrested for drunk driving case, whether or not they made the right decision by selecting a blood test or breath test. Experts in the field, although agreeing on very little, seem to be in agreement that the blood test is the more accurate. The reason for this is that when the Sheriff’s crime lab analyzes a blood sample to determine its blood alcohol content, it is simpler to quantify a percentage of alcohol in one’s bloodstream.
On the other hand the results of a breath test is determined by the use of a breathalyzer machine, which take one’s breath sample and through a much more complicated process, including heating the breath and converting the breath from a breath alcohol reading to a blood-alcohol reading. This process is not a direct process, and although it has beensdetermined to have acceptably high accuracy, is still subject to a higher potential series of errors.
One of the advantages of taking a blood test after a DUI arrest is the ability to retest once blood sample for accuracy. This is made possible since the blood sample has been preserved through the use of a preservative. Breath samples are not reserved and therefore cannot be retested.
In my 30 years experience as a DUI defense attorney I have come across hundreds of various types of inaccuracy in blood samples. These errors occur in various ways including the improper drawing of the blood, including use of alcohol — based cleansing agent. Other errors occur at the laboratory by technicians, including improperly storing and preserving a blood sample.
Errors also occur by the police and/or laboratory by not keeping a consistent and careful record of how the blood was drawn, and stored thus not providing the required chain of evidence.