The most prevalent form of measuring intoxication by the law enforcement is the breathalyzer. The device is designed to measure the levels of alcohol in the lungs and not in the breath. Thus a sip of alcohol and testing right after would not and should not register any measurable levels of alcohol.

Alcohol consumed however gets processed in the body. It gets absorbed from the mouth through throat and stomach and distributes into the bloodstream.  Alcohol­ is not digested upon absorption and remains chemically the same in the bloodstream.

As the alcohol infused blood travels through the lunge membranes it contaminates the lung’s air sacs commonly known as “alveoli” and the alveolar air.

The blood alcohol concentration (BAC) and the alveolar air correlate and the alcohol levels correspond. Thus measuring the alcohol concentration through the alveolar air and by the breathalyzer device is an accurate way of measuring the individual’s BAC but it is not flawless.  The ratio of blood to air alcohol level is approximately 2100 to one ratio. That is about 2100 milliliters (ml) of lung-air would have the same alcohol levels as 1 ml of blood.

Generally the Breathalyzer device contains:

  • An intake manifold to sample the breath of the suspect
  • Opposing glass vials containing the chemical reaction mixture
  • Photocells elements and a meter gauge to measure the color change associated with the chemical reaction

As the breath sample is processed through the device the alcohol from the breath is extracted and reduce to a liquid format whereby through a series of chemical reactions and processies, the alcohol level or the BAC is measured and displayed.

The device, the testing process and even the calibration are not always accurate and susceptible to false read.

Certain medical conditions may predispose to false-positive breath testing. For example:

  • A very low calorie diet (fasting) low-carb diet, aka ketogenic diet
  • People with type I diabetes mellitus, diabetic ketoacidosis

The common feature, the increased formation of ketone bodies can set off inaccurate results. Acetone is a volatile by-product of ketone excreted in the urine and exhaled during breath. Although, breath-alcohol tests do not detect acetone, they react to isopropanol in the same manner they do to ethanol creating potentially a false positive.

There exists another avenue that is wide open for further exploration of breath-alcohol testing devices’ susceptibilities to errors. All current evidentiary breath testing technologies are based on indirect assessment of BAC via a breath sample and on the assumption that alveolar air/blood ratio is 2100:1 — one part of alcohol in the exhaled air to 2100 parts in the blood.

This main assumption was the foundation to the main principle upon which all the breath test devices operate. This principle, which can only be applied under certain physiological conditions, mainly measuring solely alveolar breath sample and complete absorption of alcohol by the body that are rarely achievable, is a subject to many invalidation theories. Partition ratio has been shown to range anywhere between 1:1300 to 1:3000 in healthy individuals, yet 1:2100 is a conversion factor approved in the United States.

Moreover, people with chronic lung disease, also females with generally smaller lung volumes are unable to produce minimum exhaled volume necessary for valid test results. As they are prone to exhale less air, their exhaled alcohol concentration may be higher.

Breathing patter is another major factor that can affect the test results.  For example, hyperventilation will decrease exhaled breath alcohol and hypoventilation will increase it. Shallow breathing as well as breath holding can also increase exhaled breath alcohol. Higher body temperate will also result in an increased exhaled breath alcohol concentration.

Moreover, the device calibration and functionality maybe at issue and challenged.

As both the law enforcement as well as the prosecutors rely predominately on the breathalyzer results to gain a conviction, valid and effective challenge to the accuracy of the device at any level can create a reasonable doubt needed to gain an acquittal.

Contact our Washington DC Criminal Lawyer/DC DUI Lawyer to schedule an in take appointment and to evaluate your case.

Categories: Criminal Defense.