In drunk driving cases, criminal prosecutors can turn to a number of sources for evidence. In addition to field sobriety tests or breath tests conducted at the scene of an arrest, authorities might rely on blood tests, which are often viewed as a definitive measure of intoxication or sobriety. As a case in another state demonstrates, this sentiment might not always be the case.
A Tennessee man was arrested for driving under the influence of alcohol and causing a fatal accident in March 2013. State authorities drew his blood after the incident and conducted an analysis that determined his level of intoxication was three times the legal limit. However, an independently conducted blood alcohol test determined that the blood-alcohol concentration of the same blood sample was only 0.01 percent, which is well under the legal limit.
As a result of this independent blood analysis, the validity of tests coming from Tennessee's state crime lab is now a serious concern. Specifically, there are questions about whether or not the technician who performed the test on the man's blood produces accurate and consistent test results.
Since the blood evidence from this case was challenged in court, the drunk driving charges have been dropped. This case shows that mistakes can be made by authorities at any point during a criminal investigation. Not only could mistakes be made while collecting a blood sample, but crime lab technicians might also make mistakes.
The important thing to remember is that evidence of any kind should never be viewed as a "silver bullet." As such, it can be very helpful for individuals facing DUI charges to launch a strong defense, which could include a thorough, independent analysis of evidence.
Source: WSMV.com, "TN toxicology tests under scrutiny as TBI investigates lab worker" Carley Gordon, Oct. 21, 2013