Breath Alcohol Content Testing

Breath Alcohol Content Testing. BrAC. False Breath Test Results in DUI Charges

In Kansas and Missouri, drunk driving statutes make operating a vehicle with a tested blood alcohol content of .08 grams of ethanol per either 100 mL of blood or 210 L of breath. While blood tests have consistently been shown to be significantly more scientifically reliable, they are also much more expensive and invasive. Moreover, blood tests are generally more legally challenging for the police to obtain. The distinction between blood and breath tests was observed by the Kansas Supreme Court in State v. Ryce (2016), by the Missouri Supreme Court in Missouri v. McNeely (2013), and by the United States Supreme Court in Birchfield v. North Dakota (2016). Consequently, Missouri and Kansas both heavily emphasize the use of breath tests following drunk driving arrests. Unfortunately for public safety and for thousands of Missouri and Kansas drivers who are falsely accused of drunk driving, these breath tests are far from reliable. If you have been charged with drunk driving and completed a breath test, call a professional DUI lawyer today to ensure that you get the best legal defense possible!

The Intoxilyzer 9000

Kansas and Missouri both have for the last several years begun using the Intoxilyzer 9000 to collect breath test results; transitioning away from the Intoxilyzer 8000. Despite this, breath testing in both states is still highly unreliable. In the simplest possible terms, the Intoxilyzer 9000 measures the content of alcohol in a sample of air by shooting light through air in a testing chamber and measuring the amount of interference the air has on the light. It then uses those measurements to calculate the ratio of alcohol to breath (otherwise known as BrAC, or breath alcohol content), which it then expresses as grams of ethyl alcohol per 210 liters of air.

The Beer-Lambert Law

The scientific principle for testing the concentration of substances in air by measuring light absorption is the ironically named Beer-Lambert Law. Simply, light loses intensity as it moves through different substances at different rates; the rate being determined by the specific chemical. Additionally, the type of chemical has a constant influence on the loss of intensity in the light, theoretically allowing this loss in intensity to measure the presence of specific chemicals like ethyl alcohol. While this scientific principle is described as a law, it is not as generally applicable as the law of gravity. The Beer-Lambert Law only applies in very specific conditions, which means that test results that rely on it are fundamentally limited. Unfortunately, many defense attorneys are not aware of the scientific principles breath tests depend on, which prevents their clients from getting the best legal defense. If you have taken a test with the Intoxilyzer 9000, contact an Johnson County DUI attorney with years of experience in DUI defense.

Sources of Unreliability

Scientific tests are all subject to certain types of unreliability, Tests conducted by the Intoxilyzer 9000 have numerous different sources of error and unreliability. Knowing those sources of error and using those effectively in a legal defense can be a crucial element in DUI cases. Hire a DUI lawyer to look at the facts of your case to see what issues are relevant to your defense.

Inherent Margin of Error

In normal operation, the Intoxilyzer 9000 will calibrate itself by performing a series of standard operations. It will conduct an Air Blank, in which the machine pumps ordinary air through the machine while testing it for alcohol content. It will also conduct an External Standard Check, where it tests the alcohol content of the attached control dry gas cylinder. Finally, it will also do an internal diagnostic in which it checks for various internal errors. Even when the Intoxilyzer 9000 is working perfectly, there is a margin of error of .005. That means someone with an actual BrAC of .075 could still get a test result at the legal limit even in the best possible conditions! Obviously, breath tests are never administered in as perfect of conditions as the Intoxilyzer 9000 internal tests – which means that the actual margin of error for any given test is even greater than this. Hire a lawyer who will diligently review your case to see if your test was unreliably administered.

Multiple vs. Single Tests

As noted above, breath test results from the Intoxilyzer 9000 inevitably possess a margin of error. Numerous jurisdictions in the United States have responded to this inherent uncertainty and unreliability by requiring multiple tests be taken. Scientific reliability is heavily dependent on multiple tests to ensure consistency of results. Kansas and Missouri, however, do not require multiple tests to be taken. Unfortunately, this can all too easily lead to unreliable and incorrect tests to be used against people.

Chemical Interferents

Breath tests are scientifically based on the Beer-Lambert law described above. Some of the conditions limiting the application this law can be present when Intoxilyzer 9000 tests are conducted. One of those is the presence of chemical interferents. Ideally the Intoxylizer will shine IR through the test chamber which will then interact with the particles in the air and the results of that interaction will demonstrate the presence of certain particles. In practice, however, the air in the test chamber from an actual human breath will contain a variety of substances and chemicals which could impact the efficacy of the test. Even in low quantities, biological substances like those found in the human mouth and lungs can significantly decrease the reliability of Intoxilyzer 9000 tests. Acetone (which can be found somewhat commonly in human breath), tobacco smoke, moisture, and other chemicals can also have an impact on the accuracy of breath tests taken with the Intoxilyzer 9000.

Radio Interferents

Since the Intoxilyzer 9000 uses infrared light and its energy level to measure chemical contents of breath, the results are dependent upon certain electromagnetic conditions for the test. Things that create electromagnetic interference compromise the reliability of Intoxilyzer 9000 test results. Phones, radios, and other electronic devices all generate certain amounts of electromagnetic interference which can cause problems with Intoxilyzer 9000 reliability.

Homogeneity and Mixing

Another Beer-Lambert law limitation is that substances being tested must be homogenous. Practically speaking, this is impossibility even in perfect conditions. In a breath test, there are multiple chemicals and substances present in the air in a mixture that is not evenly mixed. That causes the infrared light used by the Intoxilyzer 9000 to scatter and be absorbed unpredictably thereby affecting the reliability of any test results.

Mouth Alcohol

One obvious source of error for breath tests is the presence of alcohol molecules in the mouth. If a small amount of mouth alcohol enters the Intoxilyzer 9000 during a test, it can massively exaggerate the test results. Even the most modern Intoxilyzer machines have repeatedly demonstrated unreliability at detecting the presence of mouth alcohol particles, leading to them reporting incorrect and substantially higher results.


This is far from a comprehensive list of the sorts of purely scientific issues that the Intoxilyzer 9000 can run into. There are also numerous other considerations beyond the reliability of the Intoxilyzer 9000 that impact the admissibility of your test results, and other aspects of any case. If you have been charged with drunk driving in Kansas or Missouri, call a lawyer with a strong background in defending people like you.

We Take Pride in Establishing Solid Working Relationships with Our Clients

Read What Our Former Clients Have Said

  • "Professional, informative, and vital in working with the prosecutor to secure the most favorable outcome possible".

  • "Jerry kept in constant contact with us and our son during the case and went the extra mile to plea before the judge outside and inside the courtroom".

    Joanne from Nebraska
  • Disaster diverted!!!


Get a Free Consultation!

  • Please enter your first name.
  • Please enter your last name.
  • Please enter your phone number.
    This isn't a valid phone number.
  • Please enter your email address.
    This isn't a valid email address.
  • Please make a selection.
  • Please enter a message.