Breathalyzer Device Testing and Calibration

Tempe Lawyer for DUI Defense Based on Challenging Breathalyzer Results

Law enforcement officers in Arizona use breath tests to determine whether there is alcohol in a driver’s system. Breath tests measure blood alcohol concentration (BAC). The body metabolizes alcohol in various ways, including breathing. When you inhale, you exhale gases, and if you’ve been drinking, the exhalation will include molecules of alcohol. When your BAC is .08 or more, you may be arrested and charged with DUI. You can also be charged if you are impaired while driving, even if your breath test indicates your BAC was below the legal limit. If you are concerned about Breathalyzer device testing and calibration after being charged with a DUI, you should discuss your situation with the experienced Tempe criminal defense lawyer James E. Novak.

Breathalyzer Device Testing and Calibration

The most common breath device test used in Tempe is the Intoxilyzer 8000, which is manufactured by CMI. It’s been used for 15 years dating back to the early 2000s. The Arizona Department of Safety maintains these devices and sets its operational standards. The breath test results from the machine may be admitted into evidence at trial. Under 28 A.R.S. §1323, the government must follow certain protocol when administering the test, as set forth in the Department of Public Safety regulations.

Among other criteria, a test is valid only if it uses a quantitative breath testing device for which the Department of Health Services of Health Safety has provided properly authenticated certification. Additionally, under the statute, the operator who conducts a test must possess a valid permit issued by the department of health services or the department of public safety to operate the device used to conduct the test.

Duplicate breath tests may be administered. If the tests results are within .02 alcohol concentration of each other or the person administering the test observes you for 20 minutes before administering the tests, they may be admissible.

Mouth alcohol dissipates rapidly. This can impact the test’s accuracy. When the device finds mouth alcohol, the results may be high, but the result would not be regarded as accurate. In order to have the test be accurate, you must not have consumed alcohol in the 15 minutes before taking the breath test. The most common way to do that is to handcuff the person. Additionally, the duplicate test must have a variance within .02%. In order to accomplish the duplicate test, you may be handcuffed. When the variance is beyond .02%, this is likely a sign that the test with the higher percentage was affected by mouth alcohol.


Every time a suspect takes a test, a device must be calibrated. The devices differ in how they are calibrated, but generally with the Intoxilyzer 8000, a cylinder on the side of the machine includes a gas solution with alcohol inside it for calibration. The machine is flushed through the solution immediately before and after a breath test to figure out how accurately a device can read a solution held by the cylinder. An officer should use the solution in the cylinder when you’re taking the breath test, and it must be within a certain range of accuracy.

Expert Witness

Sometimes breath tests are admitted with the testimony of an expert witness at trial through what’s known as the Deason method. A prosecutor might try to employ this approach if, for instance, you took one test, but changed your mind and didn’t take the second. The government could have an expert testify that, in spite of this, the procedures used were reliable and accurate. We may need to retain an expert to testify otherwise. It is critical to hire an experienced criminal defense attorney who works with credible experts when mounting a DUI defense.

Under Rule 702 of the Rules of Evidence, a witness who is qualified as an expert by skill, knowledge, training, experience, or education can testify in the form of an opinion. The court will only permit this, however, if her technical, scientific or other special knowledge will assist a trier of fact to understand the evidence or decide a fact in issue. The testimony must be based on data and facts; it needs to be the result of reliable methods or principles and an expert has reliable applied principles and methods to the facts of the case.

Chain of Custody

After a prosecutor has established when a sample was collected, she will need to show the blood or urine sample tested at the lab was the same sample collected from the defendant on the date of a violation and that it was not tampered with in a chain of custody. When this cannot be done, we may be able to challenge the results.

Hire Seasoned Tempe DUI Defense Attorney

James E. Novak may be able to represent you against charges of DUI. In some cases, Breathalyzer device testing and calibration represent an important aspect of a client’s defense. Mr. Novak’s experience allows him to determine the strength of a defense based on challenging Breathalyzer results. He represents those arrested in Phoenix, as well as Gilbert, Chandler, Mesa, and Maricopa County. Contact him at (480) 413-1499 or complete our online form.

Client Reviews
I was facing criminal charges with three priors in my history. Mr Novak was very helpful and got me a lighter sentence than I probably deserved. He is a great attorney and I would highly recommend him. A. T.
James worked tirelessly behind the scenes with the prosecution, to decrease my son’s charges to a more reasonable penalty. I could not have asked for a better, more professional attorney. He treated my son with the utmost respect and walked him through every step of a very difficult situation. S. G.
Attorney Novak did an outstanding job defending my son. Due to his extensive professional background within the court system, he was successfully able to defend my son during a very difficult time for my family. I highly recommend Attorney James Novak for your legal needs. T. G.