Most jurors believe that the breath test is given on the side of the road, and that it is definitive on the issue of intoxication. These two beliefs are completely wrong. There are hand-held devices that some police use to test breath on the road, but these devices are not accurate. The results are not admissible in court, and a policeman is not allowed to state that, based upon that roadside breath sample, the person who is tested is intoxicated.
Should you take the test? No, unless you have not been drinking. Marijuana, illegal drugs or prescription medication may make you intoxicated, but they will not register on this machine.
The Intoxilyzer 5000 is located at the jail, and it is in a room where it cannot be moved; where the temperature is controlled; and where there are no interfering chemicals in the air. The person must give the breath specimen voluntarily – not as a result of threats or promises of leniency. The machine must warm up. There is a keyboard for input specific to the test. There are sterile mouthpieces in cellophane packages available for each test. When the person agrees to blow into the machine, he must do so twice. Before each blow there is an air blank by the machine, and between each subject blow there is a calibration done using air from an attached reference sample device.
These machines are operated by a computer and software. In Texas, the courts do not allow access to the software program. Almost every action take by the operator, the subject and the machine itself are recorded in a database called "Black Mamba." The database contains the results of every breath test, on every machine in the State of Texas taken since about 2005. It was developed by Ray McMains when he was an employee with Texas Department of Public Safety. Access to that data is publicly available at DWI-FISS.com . There is a membership fee for access.
Using the database in this office, I am able to view the history of error messages given by the machine during subject tests. I can see the notes of the technician who maintains the machine, and I can request hardcopy of maintenance records for specific dates of interest. This is the most recent means of fighting the breath test itself: establishing problems related to the maintenance and performance of the specific machine involved. Expert testimony is sometimes needed.
A final introductory note is that there may be a constitutional issue regarding maintenance records because the technicians have been ordered to turn off the memory recording feature during maintenance. We are required to trust that the technicians are doing their jobs correctly. However, at least four of these technicians in Texas have been fired, imprisoned or suspended for maintenance issues.