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Breath Testing

"How It Works"

I. BREATH TESTING - The General Concept

It has always confused people - whether they would admit it or not - that some machine or device could take a sample of a person's BREATH and tell us what the amount of alcohol was in the person's BLOOD. At the same time, however, the same people have accepted this concept without much, if any question. As the defending of a person charged with DUI with a breath test, this MUST be understood and questioned by the attorney.

Certain presumptions must be made to support the concept of breath testing for alcohol. The most important of these is Henry's Law which relates to alcohol in water (or blood) which is:

For a fixed concentration of alcohol in water at a fixed temperature, the ratio of alcohol in air ABOVE the water is also fixed. Thus there will exist at least theoretically a constant ratio between the concentration of alcohol in the alveolar air of the lungs.

This would mean that the blood in the lowest part of the lungs, where capillaries are at their greatest concentration, would be carrying the alcohol and, due to the interior or core temperature of the person, the alcohol would be "hovering" in the gases directly above these capillaries. Alveolar air, coming from the sacks or alveoli deep in the lungs, is that which is believed to come from the "bottom" of the lungs or the last or end blow from the individual.

As this part of the air from the lungs is exhaled, the presumption is that the alcohol level will RISE as the gases exhaled come from deeper in the lungs, as the gases at the "top" of the air passageway is further away from the location where the Henry's Law/gas exchange is occurring. Once the alcohol level "plateaus", the last breath of the lungs is presumed to have now reached the machine and the sample is complete. However, Dr. Michael Hlastala, of the University of Washington, has challenged this entire concept recently, initially presented at the Third Annual Summer Session at the National College for DUI Defense in 1997 at Harvard Law School which I attended.

Foundational to this presumption is that the FURTHER presumption that the constant ratio in a human being of the amount of alcohol in this gas is one (1) part for each 2100 parts of blood. This is known at the blood/breath ratio of 2100:1, which is referenced throughout this written material. In other words, if the number of molecules of alcohol in the gas of the sample of the person is multiplied by 2100, you will have the alcohol level in his blood. As also referenced in this written material, this is a problem that is ALSO foundational in defending these cases in that this ratio can ACTUALLY vary - easily - in an individual from 1500:1 to 3000:1!!

These presumptions are the basis for any and all breath testing devices used in the world. There are many different machines that are used to test alcohol in the breath that use the infrared (IR) system (considered to be the most accurate and reliable) such as the Draeger, Intoximeter, and, of course, the Intoxilyzer which we use exclusively here in Oklahoma.

II. THE MACHINE - The Intoxilyzer 5000

A. How it works

The Intoxilyzer 5000 is basically an infrared (IR) spectrometer connected to a-not-so-sophisticated computer. Infrared spectroscopy is a system which involves reading light wave lengths. It has been long understood that certain molecules absorb certain wave lengths of light. It is the system's use of this IR absorption which results in a personís reading on the machine.

The sample of the breath to be tested or analyzed is introduced into the sample chamber. Light is flooded into the chamber via a Quartz, tungsten halogen lamp. The chamber lens gathers the light passing through the chamber and focuses it into the IR filter wheel. This wheel has filters or "eyes" to detect certain IR wave lengths. The IR detected is sent to the detector which translates the wave lengths into electric energy. This energy is sent to the processor which amplifies the reading from the filter and converts this, via the computer and its software, into a "BrAC" level at grams of alcohol per 210 liters of breath. This software assumes that you are an AVERAGE person with a 1:2100 breath/blood ratio.

The IR "reading" by the filter is caused by the absorption of that particular IR wave length by a specific molecule, i.e., ethanol. The filter wheel "sees" less of that wave length when there is absorption by any unknown in the chamber. This variance is what eventually reaches the processor.

The filter wheel on the machine here in Oklahoma series machines has three (3) filters or eyes in it. One "reads" nothing and creates a baseline. The other two are for ethanol and acetone. The reading/energy indicated as acetone (commonly emitted by persons with diabetes or blood sugar problems) absorption is supposed to be subtracted for that wave length absorption(s) when the processor converts the reading into breath alcohol concentration ("BrAC").

B. Taking the Test

In Oklahoma, every breath test must be preceded by what is called an "observation" or "deprivation" period of at least fifteen (15) minutes.  During this period of time, the person about to take the test on the Intoxilyzer 5000-D (the "label" of the particular Intoxilyzer 5000 that we use in Oklahoma) is not to eat, drink, smoke, regurgitate, or vomit.  He is, basically, not to have anything go into - or out of - his mouth.  The purpose of this deprivation period to is assure that there is nothing in the person's mouth which could contribute to a false reading - like mouth alcohol - on the Intoxilyzer 5000-D.   Importantly, at the start of this period, the Officer doing this deprivation is to check the mouth of the person to make sure there is "no foreign object".  Press Hereto see what the Board of Tests means by a foreign object).  Once this deprivation period is done, the officer can start the test of the person.

To get a test result, a person must, obviously, blow into the breath tube. This tube sets on the left side of the machine (as the operator faces the machine) and is wrapped with a black, heated, thermal wrapping and RFI antenna coiled underneath the thermal pad. The purpose of this heated wrapping is heat the tube as to remove condensation from the breath sample. The sample must be gas, without liquid, when it reaches the sample chamber. Otherwise, the reading will be falsely high. The mouthpiece is designed to "trap" some of this condensation as well. Further heating inside the machine is designed to remove the remainder of any liquid. Officers are trained to check or feel of the tube before testing the person to see if it is warm. They are not trained to inspect the plug at the bottom of the tube to see if it is plugged it and secure.

The RFI antenna is to detect radio frequency interference or electro-magnetic energy. This has been proven to cause the electronics in this machine to malfunction, giving a falsely high reading if it is not neutralized. This safe-guard will avoid this problem, if working properly, and give the officer a "RFI" prompt and/or indication on the printout. A second test is to be given, if this occurs. However, the diagnostic system of the machine will not detect if this RFI is unplugged!! It simply does not know if this feature is working or not.

Here in Oklahoma, Rules of the Board of Tests have a permissible variance between each of the two (2) breath tests to be considered valid. The variance here in Oklahoma that is acceptable between the two (2) samples is + .03%. Some states call for a variance of + .01% or + .02%. If it is greater than the specified range of variance, most states' rules like here in Oklahoma - require a re-test of the person.

The software will abort a test if an operator attempts to alter any part of the sequencing above. This feature is oft-times argued to be a "fail-safe" of the machine.

To start the test, the officer pushes the green button which sets the software program into operation. Using the attached keyboard, he then types into the unit certain identifying information following the prompts on digital read-out. The machine then begins it's cycle. Most states' software will cause at least one "air blank" to be performed (which is supposed to clean all alcohol - or other detectable substances detectable - from the sample chamber) and then a sample is collected from the person. There are many other states (including here in Oklahoma) which require two (2) samples of the personís breath for a complete test.

Once the preliminary procedures have been accomplished, the display will then read "please blow". The person is directed to blow into the machine. There is a constant "tone" sound from the start of his blow until he finishes. The officer will advise him to blow until the tone stops. Of course, however, it stops automatically when the person stops blowing, whether he has emptied his lungs OR not. The machine is NOT receiving air to measure for alcohol if this tome is NOT being heard.

The machine has received an adequate, measurable sample when the "0" to the left of the decimal point on the read-out appears. However, this is not what your officer is trained to have your client do. You will directed to continue to blow until you CAN NOT blow any longer. According to a Dr. Hlastala, the longer that you blow, the higher the reading that the machine will give the person! Instead, the Board of Tests has fixed the machines to not let the reading be seen on the digital read-out DURING the person's "blow" so you can not SEE this "0" and stop if you choose.  It is believed by Mr. Sifers that this change was in DIRECT response to his teaching this fact in the various seminars around the State of Oklahoma.

Once the test is complete as per the specific requirements by the state rules, the result(s) are printed out by a printer attached to the machine. This print-out is called an "Officerís AFFIDAVIT". If you failed or refused the test, this document is to be used by you as your driverís license for thirty (30) after your arrest. This document, ALSO, become the "the evidence of the number" in the case

III.  The NEW Machine that is coming - The Intoxilyzer 8000

By staying vigilant in keeping current - and on the cutting edge of the machines used in evidence against our clients - we  became aware a few years ago (before it was ever marketed by the company) of a new device made by CMI called the "8000".  This is CMI's new toy and is being used in several states in the Nation now.  Allegedly, this device has more "protections" against false positives and other errors that are typical with the Intoxilyzer 5000.  It uses an ADDITION filtering system to remove false readings caused by OTHER interferents.  (Go to the "BREATH TEST:  Evidence or Assumption" link on the Breath Testing Page of this site for more on this problem with breath testing's reliability).

We have become aware that the State of Oklahoma will begin using this machine at the end of 2006 or the beginning of 2007.  So as to be AHEAD of the State and it's witnesses, our attorneys will be attending a cerftification course in September of 2006 on the Intoxilyzer 8000.  When it gets here, we'll be ready to defend our clients unlike ANY OTHER LAW FIRM - just like we did and have be doing on 5000 breath test cases since 1996 - on cases with this new machine, the Intoxilzer 8000.

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