In the State of Alabama, in almost every DUI defense case, the issue of a breath test will arise. The Draeger Alcotest 7110 is the most utilized breath-testing machine within the state of Alabama. The Draeger, or Drager Company, manufactures the Alcotest 7110. Draeger is based out of Lübek, Germany.
The Alcotest 7110 is designed to measure blood alcohol levels by analyzing a person’s breath. The Alcotest 7110 uses two methods to accomplish this measurement. The first technology used is called infrared spectroscopy (IR). The second technology used is called electrochecmical cell (EC).
In theory two testing methods should provide greater reliability and legal integrity than a single method of testing, which the Intoxilyzer 5000 utilizes. Although these two testing methods are supposed to be more reliable, there are other issues that can cause a faulty reading.
One such interference is radio frequency interference. Radio frequency interference is more commonly known as electromagnetic interference. One situation where electromagnetic interference could occur is through police radios. In fact a handheld police radio keyed intermittently can affect radio frequency.
Another issue that can cause problems with the Alcotest 7110 is what has been titled the Tyndall effect. The Tyndall effect can cause an elevated reading during the optical method of analysis as it measures the absorption of light. When a person provides a breath sample, suspended solid particles, which may be located in the breath sample, can be isolated in the sample chamber and deflect infrared light. This can keep the light from striking the detector and cause the appearance of absorption. Common causes of this issue may be from an air bag deployment or common debris from repeated introduction of room air into the sample chamber.