The state of Arizona uses a machine called the Intoxilizer 5000 to determine blood alcohol levels. The Intoxilizer 5000 was developed using old technology. In fact, the Z-80 microprocessor used by the Intoxilizer 5000 was introduced over 30 years ago.

The machine utilizes infrared absorption to determine alcohol levels. A person suspected of DUI must blow into a tube. The tube leads to chamber where the suspect’s breath is collected. An infrared light shines through the chamber and tiny alcohol molecules in the breath absorb fragments of the light. The difference between the light emitted and the light received at the other end of the chamber is used to calculate a number that is ultimately compared against a .08.

The reliability of the Intoxilizer 5000 has been the subject of debate for many years. Many believe the amount of breath sampled to be too small to yield accurate results. Furthermore, opposition to the Intoxilizer 5000 claim that the device confuses other substances with alcohol therefore causes inflated results. Cigarette smoke, mints, or the consumption of foods such as bread may impact the test results.

Arizona DUI law only requires that the device perform within a 20% variance. Therefore, it is acceptable for results to be as much as 10% off. This means that if your tests results yield a .08 it is very likely that you were not driving over Arizona’s legal limit. With this in mind, the manufacture doesn’t warrant the accuracy or reliability of the tests results.

Another operational flaw of the Intoxilizer 5000 is that the machine assumes that everyone tested has a blood/breath ratio of 2100/1 (2100 parts of alcohol in the breath for every 1 part of alcohol in the blood). This assumption should not be made. Individual blood/breath ratios vary considerable. There are documented cases of individuals with blood/breath ratios as low as 1100/1. However, the Intoxilizer 5000 does not account for this.

For these reasons, the Intoxilizer 5000’s results should not be trusted.