When a person is charged with a DUI, the government makes their case using all evidence gathered during the arrest. This evidence will include the officer’s report and observations as well as the reading from any blood or breath test taken. These two pieces of evidence will make the bulk of prosecution’s case against a person, therefore if either account is inaccurate; it is in the best interest of the defense to argue its validity.
The accuracy of a breath test can be argued by demonstrating that the machine has not been properly calibrated, or it is running insufficiently. This is done by subpoenaing the maintenance records and reviewing them. If the machine has been used for a long time without having been checked for accuracy, there may be a weakness in prosecution’s case.
The reliability of blood test results may also be argued. This is done by questioning the lab that has done the testing. The lab may have contaminated the sample, may be biased, or may have even tested the sample inaccurately. To obtain a valid, accurate sample, the person charged with the DUI has the right to have the blood sample tested by an independent lab. They also have a right to go to their own doctor and have their blood tested. However, this does weakens the strength of the blood sample as evidence because many hours have passed since the original arrest. Consequently, the sample will not reflect an accurate reading of the Blood Alcohol Level.