Challenging breath test evidence

Posted by Craig Penrod | Dec 03, 2013 | 0 Comments

Under the implied consent law in the state of Arizona, an individual who is arrested for driving under the influence (DUI) of alcohol, the arresting law enforcement officer as a part of their investigation can request that the individual submit to a test or tests of their breath, blood or urine as a means of determining breath or blood alcohol concentration. Those tests must be conducted within two hours of the time of driving or the time of the traffic stop.

In the state of Arizona, the Intoxilyzer 5000 and the Intoxilyzer 8000 are the devices most commonly used for evidentiary breath analysis (EBT). Both devices are manufactured by CMI in Owensboro, Ky. The Intoxilyzer 5000 has been in service and used by law enforcement in the state of Arizona for at least 20 years. The Intoxilyzer 8000 is gradually replacing the Intoxilyzer 5000, and has been used by law enforcement in at least five other states. In Arizona, if you are cited for DUI and the charge is based upon breath test evidence it is important that you should consult experienced Phoenix and Tempe DUI lawyers like those associated with the Law Offices of Craig W. Penrod, P.C.

The Intoxilyzer 5000 and the Intoxilyzer 8000 use infrared spectroscopy technology to detect ethyl alcohol molecules in a breath test sample in order to measure breath alcohol content and convert it into a numerical reading or readings equivalent to blood alcohol taken directly from the blood of an individual. This conversion factor, which is different for each individual, is called a partition ratio.

The infrared spectroscopy technology uses a particular infrared energy wavelengths in the range of 3.3 to 3.5 microns and, for some devices, at 9.5 microns. Many other chemicals have wavelengths in these ranges. Thus, the devices are capable of reading non-alcohol substances as alcohol, artificially inflating numerical readings on printer cards for the Intoxilyzer 5000 and Intoxilyzer 8000. The result can be that an individual's true BrAC readings on the devices is overstated.

The device is also subject to electro-magnetic and radio frequency interference (RFI), which may also falsely elevate readings on printer cards. It is important that any radio frequency devices are kept away from the breath test machine while it is being used to test an individual's breath for alcohol. If the device encounters radio frequencies, the test could be affected with the result being a drastically inflated report of breath alcohol results. In response to this issue the manufacturer of the Intoxilyzer 8000, CMI, has installed a radio frequency detector on the front of the breath test device as a warning to officers that the device is detecting radio frequencies during its operation. The most common source of radio frequency interference can be the radio equipment used by the law enforcement officer who is conducting the test. Most law enforcement officers have learned to turn off their portable radios prior to conducting breath tests.

The Intoxilyzer 8000 was designed as a compact EBT that can be used in either a stationary mode, such as in a law enforcement substation or in a mobile capacity, as in the back of a law enforcement vehicle. Although the Intoxilyzer 8000 was designed to be a replacement for the Intoxilyzer 5000 it's been questioned in the state of Tennessee in the past and has fallen under criticism in the state of Ohio in recent months.

Known problems and issues with these devices can lead to breath test results be precluded or suppressed. The prosecutor will not be allowed to use that breath test evidence during any subsequent trial. If sufficient challenges to breath results can be raised during a trial creating reasonable doubts regarding the accuracy and reliability of test results, it can make the difference between winning and losing a DUI criminal case for a client.

It is important that your DUI legal situation should be handled by expert professionals with the experience possessed by the attorneys at the Law Offices of Craig W. Penrod, P.C.

About the Author

Craig Penrod

Craig W. Penrod was born and raised in Arizona and has practiced criminal defense for over 30 years. Mr. Penrod is a member of the State Bar of Arizona, Maricopa County Bar Association, State of Nevada Bar Association, American Bar Association, American Trial Lawyers Association, Arizona Trial Lawyers Association, Nevada Trial Lawyers Association, Arizona Attorneys for Criminal Justice and the National Association of Criminal Defense Lawyers.


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