In 1969, Senate Bill 74 of the 61st Texas Legislature promulgated authority to the Department of Public Safety to establish breath alcohol test standards. The Department created the Office of the Scientific Director and developed rules governing evidential breath testing. These rules are contained in the Texas Administrative Code Title 37 Chapter 19 and are commonly known as the Texas Breath Alcohol Testing Regulations.

The Scientific Director's Office administers and regulates the state breath alcohol testing program through technical supervisors in compliance with the Texas Breath Alcohol Testing Regulations. All analyses conducted by state, county, and city law enforcement officials are performed in accordance with these regulations, which require the certification of all aspects of breath testing. These breath alcohol analyses are performed in conjunction with various alcohol related criminal offenses and the enforcement of commercial driver license statutes.

The Scientific Director's Office directly manages the Department's technical supervisors, and administratively manages technical supervisors employed by other agencies. Duties include certification of 340 breath testing instrument locations and 4,200 breath test operators. The office also provides expert testimony as needed in contested criminal, civil, and administrative breath test cases.

In addition to evidential breath testing, the Office of the Scientific Director regulates the breath alcohol ignition interlock device industry within the State. Breath alcohol ignition interlock devices (BAIID) require the operator of a motor vehicle to submit a sample of alcohol free breath prior to engaging the ignition. Many courts and probation officers mandate the installation of such devices as a condition of probation for individuals convicted of alcohol related offenses. The Texas Ignition Interlock Device Regulations of Title 37 Chapter 19 Texas Administrative Code govern BAIID activity.

For many years, the only means of testing blood alcohol through breath analysis was with instruments using the wet chemical technique, such as the Breathalyzer. In 1972, however, Omicron Systems Corporation introduced a machine using a new method of analysis based on infrared spectrophotometry (also called infrared spectroscopy or, simply, infrared absorption). Omicron’s Model 4011 was faster, easier to use, and more economical and convenient that the Breathalyzer. There was no evidence, however, that the device was any more accurate; in fact, because of greater risk of nonspecific analysis, the machine was determined by many to be less reliable.

A few years after introducing the Intoxilyzer, Omicron sold all rights to the instrument to CMI, Inc. Subsequently, CMI introduced a new, state-of-the-art breath-testing device: THE Model 5000. This machine also utilized infrared spectrophotometry in its analysis, but incorporated an internal computer and various supposedly “fail-safe” features. Further, CMI claimed to solve the non-specificity problem by using three separate wavelength band filter (subsequent versions employed five filters). In addition, the Model 5000 incorporated an “interference detector” that would theoretically advise the operator whenever foreign substances such as acetone are present in the breath. And acetaldehyde detectors and radio frequency detectors were available as options. Experience, however, has proven that each of these features is less than reliable in ensuring accurate results.

As of this writing, CMI was in the process of developing its newest breathalcohol machine, the Intoxilyzer 8000. in apparent response to the increasing popularity of Draeger’s newer Alcotest 7110 and Intoximeter’s ECIOR, the model 8000 will have two filter wheels rather than just one, which will be capable of reading nine channels from the 3.0+- to 9.0+-micron range. This should improve—not eliminate—specificity. However, the device will apparently not have the even greater specificity afforded by the addition of a second electrochemical fuel cell system as is found in the Draeger and in the Intoximeter EC/IR.

Infrared spectrophotometric analysis is based upon the fact that different molecules absorb light energy at different frequencies. Water, for example, will absorb infrared light whose wavelength is 2.7 microns: when this 2.7-micron light passes through water vapor, its vibrations are absorbed by bonds between the oxygen and hydrogen atoms in the water molecule, causing the atoms to vibrate more strongly and the 2.7- micron energy to disappear.

A complex molecule has a number of different sets of bonds, and neighboring bonds will influence a basic vibration, changing it slightly. Ethyl alcohol has its hydrogen-oxygen bond vibrations shifted slightly by the nearby presence of carbon-hydrogen bonds. As a result, most of the absorption of light by ethyl alcohol will take place in the band range from 3.380 to 3.398 microns. The Intoxilyzer, then, simply shoots a beam of infrared light through the captured breath sample and measures how much of it is absorbed in that range; the more absorption, the higher the blood-alcohol concentration.

Mechanically, the heart of the Intoxilyzer 5000 is a nickel-plated sample chamber of 81cc capacity heated to 45 degrees centigrade. This chamber captures the breath sample from the subject being tested. A quartz iodide lamp at one end of the chamber then emits infrared light energy, which is directed through the breath in the chamber by a lens. At the opposite end of the chamber, a second lens focuses the energy leaving the chamber through three rotating filters and onto an energy detector.

The more recent versions of the 5000 have five of these light energy filters. The first filter is the internal reference standard, designed to produce light waves at ethyl alcohol’s spectrum by being centered at 3.80 microns. Two filter, at 3.40 and 3.47 microns, are designed to distinguish between alcohol and the commonly encountered interferent acetone. Two more filters have been added to detect acetaldehyde (like acetone, produced in the body) and toluene (a common industrial compound). Properly calibrated, these filters are designed to detect and subtract out from the final reading any interfering substance.

When the unabsorbed infrared light reaches the energy detector, the amount is then measured and this information is transmitted to an internal Z-80 computer. This primitive computer compares the amount measured to a “ zero reference point”—the amount of infrared energy reaching the detector when the sample chamber was earlier filled with ambient (room) air. The difference—theoretically the amount of light absorbed by the subject’s breath sample—is then calculated. Based on the amount of alcohol in the breath thus measured, the computer then calculates the amount of alcohol in the subject’s blood by applying an average blood/ breath partition ratio of 2100:1.

Additionally, the various “fail-safe” mechanisms available as standard or optional features have proven unreliable. As mentioned, the Intoxilyzer theoretically detects the presence of acetone (and in later models, acetaldehyde and toluene) on the breath, registers “interferent” on the visual display, and automatically subtracts the acetone from the final reading. Quite simply, extensive tests have shown that the detectors do not always work.

The Intoxilyzer 5000 also has circuitry that supposedly detects the presence of radio frequency interference and aborts the test. Again, law enforcement agencies routinely deny that RFI exists as a problem. And again, tests in the field and in the laboratory have shown that these detectors (which can be desensitized by technicians to avoid constant aborted tests) are not reliable.

The machine also features a “slope detector,” which, in theory, determines whether there is alcohol or an interfering substance present in the mouth. When mouth alcohol is present, the alcohol content curve reaches a maximum and then declines rapidly due to depletion of the mouth alcohol; this decline is recognized by the machine’s computer, resulting in the message “invalid sample.” Once again, however, the feature is defective.

Of course, counsel can always ask the officer/operator or forensic expert, “If the slope detector detects mouth alcohol, why is it necessary to have a 15- or 20- minute observation period prior to administering the test?”

Relatively recently, CMI added an additional feature to the Model 5000 which analyzes the ambient (room) air that is used to purge the sample chamber. If the air is contaminated by alcohol vapor, the machine will, theoretically, display “ambient failed” and the printout will state “invalid test check ambient conditions.” As with other “fail-safe” devices on the machines, the efficacy of this new feature is open to question.

Counsel dealing with a Model 5000 can confront the state’s expert with the manufacturer’s own recognition of an inherent defect in the machine. CMI has recently developed and offered for sale a newer version of the Model 5000: the Intoxilyzer Model 5000/568G. The main difference between this and the previous model is that it has non-reactive breath chamber. The chamber of the previous 5000s is nickel-coated and can develop oxide build-up. This oxide in the walls of the chamber can absorb ethanol and water vapor, which can then be released into captured breath samples, giving a falsely high reading.

The fact that the manufacturers of the machines offer detectors for acetone, acetaldehyde, mouth alcohol, contaminated ambient air, and RFI constitutes solid evidence for the existence and impact of these problems. Similarly, the production of a new model of the machine featuring a chamber that avoids oxide buildup is a clear recognition that previous models suffer from this defect.

The maintenance and calibration of the particular Intoxilyzer used in the client’s case should also be investigated for possible malfunctions or erroneous results in the past or in the use of the machine since the test. Again, most states have statutory requirements for the regular maintenance of breath-analyzing instruments, as well as for their calibration. Any deviation from these requirements should be noted, particularly any malfunctions of the instrument in the past, any erroneous readings, or any recent periods of time without maintenance or calibration. The Intoxilyzer should have a maintenance log and a calibration log that should indicate any abnormalities. Even if the machine has been maintained and calibrated properly for the past several months, the jury will be interested in knowing that it has had problems in the more distant past—that is, that it is fully capable of malfunctioning.

Again, most jurisdictions require proof that the instrument was in correct working order as a foundational requisite to the admissibility of the test results. Failure to show at least proper calibration at specified time intervals should preclude use of any test results at trial. Certainly, any significant indications in the records that the machine was functioning improperly should be grounds for exclusion. And in some states, the Intoxilyzer must have received a “certificate of inspection” within a specified period of time prior to the administration of the test in question.

Even assuming a perfectly maintained and calibrated machine, however, infrared spectroscopic testing devices have proven to produce results inconsistent with one another. In Alpert, Keiser, and Syzmanski, “Theory and Practice of Infrared Spectroscopy,” a study is reported in which laboratory spectroscopic tests, considered more reliable than spectroscopic tests conducted by law enforcement in the field, showed instrument-to-instrument variations of up to 20 percent of the measured results.

As with other breath-testing devices, the Intoxilyzer depends on the presumption that the subject’s blood-to-alveolar air ratio is exactly 1:2100, a false presumption in most cases and one that can result in an error of as much as .03 or more in the final reading.

The single greatest flaw in the Intoxilyzer itself—and the most productive area for cross-examination—is the machine’s inherent lack of specificity. The technical reason for this lack of specificity is that the Intoxilyzer is not designed to detect the molecule of ethyl alcohol (ethanol), but rather only a part of that molecule, the methyl group. In other words, it is the methyl group in the ethyl alcohol compound that is absorbing the infrared light, resulting in the eventual blood-alcohol reading. Thus the machine will “detect” any chemical compound and identify it as ethyl alcohol if it contains a methyl group compound within its molecular structure. The Intoxilyzer only assumes that the methyl group is a part of an ethyl alcohol compound.

No matter what the manufacturer may claim, the prosecution’s chemical expert will have to admit a simple fact: The absorption in the Intoxilyzer could be caused by substances other than ethanol. Thus one can never be sure that what the Intoxilyzer is measuring is alcohol.

A number of scientific studies have confirmed the practical reality of this problem. For example, in Caldwell and Kim, “The Response of the Intoxilyzer 5000 for Five Potential Interfering Substances,” researchers found that commonly encountered industrial chemicals (which can easily be absorbed in the work environment and retained for hours afterwards) such as toluene, xylene, and isopropanol, will register as “alcohol” on the machine. The scientists further concluded that, for example, “home hobbyists using toluene-based glues or workers in the painting industry would contain toluene on their breaths at concentrations above (endogenous) background levels.”

The Intoxilyzer machine is fully capable of electrical or mechanical malfunctions, as is any machine. The accuracy of the Intoxilyzer depends, among other things, on the intensity of the light that is beamed through the breath sample; the final reading is determined by the amount of the light that is absorbed by the alcoholic vapor. Thus any reduction in the intensity of the light from the quartz-iodide lamp bulb in the Intoxilyzer will register as the presence of alcohol, and the greater the reduction, the higher the reading. A malfunction in the bulb, then, or a drop in the line voltage (the bulb is designed to perform at 105 to 130 volts) could result in a false reading. If the voltage falls below 95 volts, the machine is designed to abort the test. However, a lesser voltage drop or a drop at the end of the 10-second test interval would not necessarily trigger the “abort” circuit. Of course, the abort circuit is not free from malfunctions, either.

The effects of these fluctuations in the light source of Intoxilyzers has been discussed in Smith, “Science, the Intoxilyzer, and Breath Alcohol Testing.” A dimming of the light would appear as a decrease in absorbance, resulting in a higher breath-test result. As the author points out, this can be caused by, among other things, a decrease in the transparency of the bulb wall and alteration of filament characteristics—both natural results of use and age.

These and other problems are theoretically prevented by the regulation of current to the filaments by the instrument’s “automatic gain control” (AGC). Normally, the AGC compensates for some problems by increasing current through the filament, raising its temperature and level of light. The AGC is, however, far from foolproof. For example, components can deteriorate to the point that the AGC cannot compensate for the decreased brightness.

Recognizing this problem, the manufacturers have incorporated a circuit whereby a minus sign on the display lights up to warn the operator that the AGC cannot sufficiently compensate, and that a falsely high reading could result. The trouble with this is that the operator’s manual does not advise the testing officer as to what this minus sign indication means: Unless the officer has been independently advised of the significance of the minus sign, he will continue with the test, ignorant of the problem.

Counsel should also consider the various potential sources of malfunction the Intoxilyzer attributable to its sensitive but critically important system of optics. It is, of course, the measurement of non-absorbed infrared light that determines the ultimate blood-alcohol level. The optics of the Intoxilyzer consist of a light source, fused quartz lenses for collimating and focusing the light beam, windows to seal the sample cell, a series of reflectors to lengthen the optical path of the sample cell, a narrow-band infrared filter, and a lead sulfide infrared detector. The light source is a quartz iodide lamp, which produces light over a wide spectral range including both visible and infrared.

The possibility of a power surge should not be overlooked in cross-examination. An unpredictable fluctuation in line voltage can adversely affect the accuracy of the Intoxilyzer reading.

One of the problems that has developed during the use of the Intoxilyzer is electrical interference from nearby radio transmissions. Just as television sets sometimes pick up transmissions from amateur radio operators, so can the Intoxilyzer pick up and convert signals. In fact, it has been estimated by electrical engineers that the Intoxilyzer contains at least 100 components that are capable of picking up and converting extraneous signals. In one experiment conducted at a police station, a radio transmitter was turned on during the testing of an individual with a known blood-alcohol level of .07 percent. This individual was tested successfully twice at .07 percent, and then the nearby transmitter was turned on: The Intoxilyzer registered a reading of .14 percent—twice the true blood-alcohol level.

In summary, there are a number of ways for a Board Certified Criminal Law Specialist to effectively challenge the breath test result. The following are just a few examples:

• Breath/Blood Partition Ratio: Research suggests that you can have two different people of the same gender, size and weight, who consume the same amount of alcohol, yet their breath alcohol readings can differ by as much as 42%! Only an effective courtroom lawyer can point this out to a jury.
• Nonspecificity: The machine fails to identify ethanol to the exclusion of all other chemical compounds. In other words, the machine can mistake other compounds for alcohol.
• Mouth Alcohol: Alcohol in the mouth can result in a falsely high reading.
• Testing during “absorptive” state: Due to the differing alcohol concentrations in the arterial and venous systems during absorption of alcohol (this can last anywhere between 15 minutes and 2 hours, depending upon your particular circumstances) some leading experts suggest that reliable breath testing cannot occur during the absorptive state.
• Hematocrit: Different people have a different amount of solids in their blood, such as red blood cells. The machine assumes a certain proportion, but if the person’s is different, the result can be biased and inaccurate.
• Body Temperature: It is well established that the higher a person’s body and breath temperature, the higher the breath test reading.
• Breathing Technique: Breathing technique can affect the breath test result by up to 30%.
• Stress: tress can affect blood pressure and breath test readings.
• Used Mouthpieces: Regulations require clean mouthpieces for each test. Used mouthpieces could contain residual alcohol.
• Simulator Calibration: Improper calibration of the reference solution can result in an improper reading.
• Ambient Air: Rooms where DWI suspects are routinely tested on a breath machine may contain the exhaled breath of those suspects who have been previously tested. The result is that the sample chamber could be purged with alcohol-polluted air.
• Incomplete Purging: An incomplete purging cycle during the machine’s operation sequence can result in improper readings.
• Radio Frequency Interference (RFI): Research suggests that RFI can affect the result by up to 40%.
• Testing after an Auto Collision: This can result in stress and high blood pressure.

One of the many things that DWI lawyers present to juries in breath test cases is that the software that actually calculates the number that it reports is kept secret. The police technical supervisor will claim that the reason it is secret is that it is “proprietary,” but good DWI lawyers know how to bring that out as a trial issue. This software contains what is called the “source code” of the intoxilyzer. Since this is a major issue in DWI trials, we have excerpted the following article from DWI Journal-Law & Science, which presents some interesting “source code” information:

Source code basically refers to the computer program that runs the breath testing equipment. “Source code” may be defined as, “code written by a programmer in a high-level language and readable by people but not computers.” Source code must be converted to object code or machine language before a computer can read or execute the program. What makes breath test devices largely unique among measuring devices is that after the amount of alcohol in the breath sample is measured, a variety of mathematical calculations must be performed to make the numbers relevant to the human system. In other words, to make the raw number relevant to the question at hand, does the motorist have an unlawful bodily alcohol level?

The questions posed by source code litigation are essentially four-fold. First, are the mathematical equations employed by the particular breath testing equipment properly formulated, calculated and applied, second, is the code acceptable to the relevant scientific community, third, has the code been subjected to an appropriate level of scientific scrutiny both inside and outside of the breath testing equipment itself, and fourth, have any changes to the code been made after the device was approved for use by law enforcement? The answers to these questions govern whether or not it can be persuasively argued that the test results should be excluded on the basis that the state cannot guarantee that they are reliable enough to sustain a criminal conviction. A complete understanding of this issue however will require a more vivid understanding of the science behind breath testing.

The first thing that a breath testing device must be able to do properly is assure that an appropriate breath sample has been collected from the motorist. For example, breath testing equipment measures the flow rate of the breath sample as it is delivered by the motorist, and in order for the sample to be accepted, certain preprogrammed parameters must be met. While these parameters vary from manufacturer to manufacturer, it remains a critical calculation because a fundamental theory of breath testing for forensic purposes is that only deep lung air be analyzed.

A related calculation is based on a breath/ blood conversion ration, and in the forensic setting this conversion is necessary because breath alcohol is only relevant as it relates to a comparative blood alcohol level. Thus, the breath testing equipment must covert the breath alcohol measurement to a comparative blood alcohol measurement. This conversion is required because breath alcohol does not impair or intoxicate, and it is only after the alcohol has been distributed throughout the body via the blood that the alcohol can cause the brain to be affected. This conversion is based on “Henry’s Law”, which states that in a closed system, the amount of alcohol in a liquid will reach equilibrium with amount of alcohol in the air above the liquid. When applied to breath testing, the liquid is of course blood, and the air is the breath. The closed system is the lungs. Henry’s law says that for drunk driving purposes a particular ratio(at a constant pressure and temperature) can be assigned to this system, and the ratio commonly accepted for law enforcement purposes is 2100/1. So, according to the theory, for every one molecule of alcohol in the breath, there are 2100 molecules of alcohol in the blood. Thus, in order for the breath test result to have relevance in drunk driving law enforcement, the source code used in the breath testing equipment must incorporate mathematical functions that will allow it to apply Henry’s Law, along with the 2100/1 ratio.

Another calculation of great significance is loosely termed “slope detection.” The purpose of slope detection is to allow the breath testing equipment to discern the presence of mouth alcohol because this would invalidate the test. The operator would know mouth alcohol has been detected because the equipment would produce an error message or status code that reads “invalid sample.” Slope detectors are also used to help assure that alveolar (deep lung) air actually composes the breath that is being tested. This is essential because in order for Henry’s Law to have any applicability, deep lung air must be measured because the deep lung tissue most closely approximates a closed system. Slope detection is an essential safeguard over the breath test results, and like Henry’s Law, it is totally dependant on properly formulated source code.

Looking again at source code the question is either or not the math used to make these conversions and calculations were properly formulated by equipment manufacturer when they developed the particular breath test machine used, and also, whether or not this math was properly programmed into the source code. The only way to know this would be to have an independent computer expert look at the code, and this is often the very goal and purpose of source code litigation. If these calculations are in any way invalid, that is, they don’t properly calculate the breath alcohol number in a way that is forensically acceptable, then the breath test results should not be admitted into evidence during drunk driving prosecutions. So, if inspections of the source code revealed and definitively determined that problems existed this would of course have a dramatic and deleterious impact on drunk driving prosecutions.

One might assume that as the equipment was being developed, each manufacturer would have done a great deal of internal testing during the production of their equipment, which presumably would have included compliance testing the source code in some way. The only way to confirm that the internal testing has integrity however, would be to independently test the code, either outside the company or outside the breath testing “box.” It is within the realm of possibilities that the code is so riddled with errors that the validity or accuracy of breath test results could not be guaranteed, or that the code is so badly written that it could not carry out its intended functions. Independent testing is required to either prove or disprove these conjectures.

In scientific circles, this type of independent testing is called peer review. Peer review (also known as “refereeing”) is a screening process used prior to the publication of manuscripts in scientific journals and in the awarding of funding for research. Peer review is used by publishers and funding agencies to select and to screen submissions for accuracy. In fact, peer review is a fundamental for publications that wish to assure that authors meet the standards of their discipline. Publications and awards that have not undergone peer review are often regarded with suspicion by scholars and professionals. The purpose of peer review is to help increase the likelihood that substantive flaws in methodology will be detected.

It appears that the no breath testing source code has ever undergone any type of true peer review. In an ideal situation the peer review process would have been conducted before the source code for the breath testing equipment was “approved” for state or federal use.

A significant aspect to the source code litigation has been to obtain the source code so that it can be submitted to this type of testing by the relevant scientific community. Until such independent testing occurs in an unequivocal way, source code litigation will likely continue.