Most DUI cases involve the alleged consumption of excessive amounts of alcohol. If the driver is under 21, many states have a “Zero Tolerance” policy, meaning that any amount of alcohol in a driver under 21 years of age is grounds for a DUI conviction.
In almost all jurisdictions, the legal limit for an adult Blood Alcohol Content (BAC) is 0.8%. While it is possible for an adult to be convicted of a DUI with a BAC below .8%, it is generally an essential part of any DUI case for the prosecution to prove BAC that exceeds legal limit.
BAC is legally determined through either a breath test, urine test, or blood sample test. An essential element in defending a DUI case involves attacking the prosecutions allegation of BAC. The following are tried methods of attacking BAC:
Blood Alcohol Testing Records Generally
There is a variety of information that should be obtained from the laboratory where a blood test is performed. This includes:
1. Laboratory Protocols and Procedures
2. Gas Chromatographs and Mass Spectrometer Maintenance Records
3. Proficiency Records for the laboratory itself, and for the Technician
Once this information is received, counsel should forward it to an expert for an independent review, where possible.
National Standards (NCCLS)
There are several organizations that issue guidelines for blood alcohol testing in the laboratory, but the NCCLS Blood Alcohol Testing in the Clinical Laboratory: Approved Guidelines CLSI / NCCLS T/DM06-A, Volume 17 Number 14, (1997) is the gold standard of guidelines.
Inspecting the Breath-Testing and Booking Room
Getting a video of the breath testing and booking room can be helpful. It may show that you may not have been observed during the mandatory 20 minute observation period, if the ‘observer’ was, for example also typing the defendant’s information into the breath device some 20 feet away with his back to the defendant. It may also reveal steps that the defendant had to traverse, and any alcohols or volatiles in the room (ambient air issue) and radio transmitting equipment (radio frequency interference issue) .
Independently Testing the Breath Device
On occasion, trial courts have allowed the defendant and his expert access to the breath machine to perform independent testing. The expert will generally be interested in determining whether the instrument can pick up interfering substances. The expert will normally prepare a simulator solution that contains the isopropanol or methanol (or other substance).
Check out this link for more information about alcohol dui.