Breath Tests – DUI Attorneys – My AZ Legal Team

Did you submit or were you required to take a breath test?  Have you spoken with an experienced DUI attorney concerning your breath test?

If you’ve been charged with DUI in Arizona you likely were subjected to a breath and or blood test in order to determine your blood alcohol concentration (BAC).  There are three major types of breath testing devices.  The first device is a breathalyzer that uses a chemical reaction to produce a color change.  The second device, an intoxilyzer, determines your BAC by infared spectroscopy.  Finally, an Alcosensor III or IV detects a chemical reaction of alcohol in a fuel cell.  In Arizona, breath tests are mainly conducted by two machines, either the Intoxilyzer 5000EN or the Intoxilyzer 8000.  Although these machines provide instantaneous results, there is controversy in the scientific community over the accuracy of the these machines.  In Arizona police are using blood tests more than breath tests because they are more accurate.

Breath Test Defenses

If you blew above the legal limit of .08 in Arizona it doesn’t mean you will automatically be convicted of DUI.  A skilled Glendale DUI lawyer will spot any issues related to your blood tests and can use this information to your advantage in your criminal case or MVD hearing.  Some common defenses to the accuracy of the breath test results include the following:

Machine Error:  The machine most commonly used in Arizona, the Intoxilyzer 8000, has a 10% random error.

Breathing Technique:  How hard you blow into the machine can affect the results of your BAC by as much as 15%.

Calibration:  The machines were not properly calibrated.  The breath testing machines must follow mandatory maintenance schedules to ensure they are working properly. 

Extenuating Factors:  Outside factors may cause the breath test machine to give a false reading.  For example, a diabetic with a high level of acetone

Alcohol in Your Mouth:  The machine may detect alcohol on your breath that has nothing to do with your level of impairment.  For example, if you used mouthwash prior to the test the machine could be picking up trace amounts of the alcohol in your mouth as opposed to what is on your breath.

Hematrocrit:  Hermatocrit is the ratio of solids to liquids in your blood and can alter the results of your blood alcohol content by as much as 14%.

Partition Ratio:  Partition ratio is the ratio of alcohol in your blood to the alcohol in your breath.  The partition ratio in humans vary significantly but the machine assumes each subject has the same ratio.

Human Error:  The operator may not have followed proper procedures in administering the breath tests.

Breath Temperature:   The machines are set to 34 degrees Celsius when the average breath temperature is 35 degrees Celsius; as a result, the machine overestimates your BAC by about 8.6%.

Radio Waves:  Interference by radio waves causing false results.