Radio Frequency Interference Can Inflate Your DUI Breath Test Results

Posted on January 31, 2011 in Breath Alcohol Testing

In Arizona, there is only one approved breath alcohol testing device for DUI suspects – the Intoxilyzer 8000. This breath test machine works by utilizing an infrared light as its primary detection mechanism for breath alcohol concentration (BAC). As a result, it is important that there is not any radio frequency devices anywhere near the breath testmachine while it is testing someone’s breath for alcohol. If the device encounters radio frequencies, they could interfere with the test and drastically inflate the reported breath alcohol results!

The manufacturer of the Intoxilyzer 8000, CMI, knows this and installed a radio frequency detector in front of the breath test machine to warn police if the machine is detecting radio frequencies during the time it is being operated. The most common source of radio frequency interference comes from the police officer’s own radio equipment. Well-trainedpolice officers will turn off their radios before administering breath tests.

However, it is important to note that the manufacturer only installed the radio frequency detector across the front of the machine. I suspect they assumed that the breath test machine would only be used to test DUI suspects in police stations, placed against a wall. Since most police stations are constructed of brick or block, the radio frequency detectordoes the trick.

However, Arizona’s increasingly aggressive DUI apprehension tactics have brought the breath test machines out of the police station and into the front seats of police cruisers and mobile police units. And, since police cars and mobile units are obviously not constructed of block or brick, the machine’s back and sides are often exposed to radiofrequency interference, with no way of detecting it.

So, how can this affect your DUI case, you ask? Well, if you were arrested by say Tempe Police or the Arizona DPS, taken to a mobile unit to have your breath tested, and your breath alcohol results were much higher than you thought they should be based on what you drank, you may have been the victim of radio frequency interference inflating your breathalcohol results. It is best to consult with an experienced DUI defense attorney to determine what can be done to help with your DUI case.