Challenging DUI Breath Testing: The Timing of the Pretest Deprivation Period

Arizona law enforcement often uses breath-testing devices to determine the blood-alcohol concentration (BAC) of a person suspected of DUI.  The Intoxilyzer 8000 is commonly used in Maricopa County.  When a person is suspected of DUI, he is generally requested to blow twice into an Intoxilyzer; this is referred to as “duplicate breath testing.”

The Department of Public Safety (DPS) has issued regulations for duplicate breath testing, which it defines as “two consecutive breath tests that immediately follow a deprivation period, agree within 0.020…of each other...”

In addition, the Department of Public Safety defines a deprivation period as “at least a 15-minute period immediately prior to a duplicate breath test during which period the subject has not ingested any alcoholic beverage or other fluids, eaten, vomited, smoked or placed any foreign object in the mouth.”  Breath-testing experts have stated that the deprivation period is critical to the breath-testing process. (See Kurt Dubowski, “Quality Assurance in Breath-Alcohol Analysis,” Journal of Analytical Toxicology, Vol. 18, October 1994.)
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ARIZONA DUI LAWS PROHIBIT IMPAIRED DRIVING, NOT JUST "DRUNK DRIVING."

It is commonly believed that “drunk driving” is the reason for a DUI charge. However, DUI stands for “driving under the influence” of alcohol or drugs. Under Arizona law, you do not have to be “drunk” to be convicted of DUI. Rather, the law requires only that your driving be impaired by alcohol; Arizona law provides that you cannot drive if your ability to do so is impaired to any degree.

When you are arrested for DUI, you generally receive two types of charges. The first alleges that you were driving while impaired by alcohol or drugs to at least “the slightest degree.” Thus, to violate the statute, you do not have to be falling-down drunk. Rather, a slight impairment of your ability to drive, due to alcohol, violates the law.

The second type of charge you receive when arrested for DUI relates to your blood-alcohol concentration (BAC). For a basic DUI allegation, you’re charged with having a BAC greater than .08 percent within two hours of driving. If your BAC is greater than .150, you may receive an additional charge of Extreme DUI (or if above .200 a "super-extreme DUI.")  These are sometimes referred to as “per se” charges, meaning that if the State can prove your BAC is above a certain limit, that alone proves a violation of the DUI statute.

Many “per se” violations are defended on the grounds that the means used to determine one’s BAC have a large range of accuracy. That is, even if the device used to test your breath or blood was working perfectly, your BAC may actually be lower than indicated. The State concedes that this range of accuracy exists. However, the real debate is over the extent of this range.

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