Intoxilyzer 5000

Many people voluntarily submit to a breath test, often because they genuinely feel they are not intoxicated when arrested. Of these, many people fail the breath test, then later vehemently disagree with the results. While the evidence may seem relatively certain at the time, it is VERY important to remember that a variety of factors can lead to an inaccurate reading. Regardless of your situation, it is imperative that you retain the services of a skilled criminal defense attorney who has researched and is familiar with the Intoxilyzer 5000 to help sort through the details of your arrest.

The Law Offices of Carl David Ceder can help you with any DWI breath test charge you may be accused of. Please call Carl and/or make contact with his legal team at 214.702.CARL(2275) or 469.2000.DWI(394) to discuss your case now. Carl is a certified technician in the Intoxilyzer 5000, which is the breath testing device used by law enforcement in Texas. He is equipped to fight any charge of DWI, including breath test cases.  Do not think your case is not worth fighting for JUST BECAUSE THERE IS A BREATH TEST! Click here to read more.

20 ways to attack the breath test and how the Intoxilyzer 5000 Model 68EN can lead to a false-positive result:

1. Partition Ratio

The Intoxilyzer 5000EN operates on the presumption that there is a mathematical relationship between the concentration of alcohol present in a person's breath and the concentration of alcohol present in their blood. The machine assumes that the concentration of alcohol present in the person's blood equals the concentration of alcohol present in 2100 milliliters of air. However, this assumed "partition ratio" can vary from 1300:1 to 3100:1 (or wider among individuals and within a given individual over different intervals). As such, this assumption can lead to a very high false-positive rate when an individual happens to have a partition ratio below the 2100:1 assumed rate which the machine uses to calculate every result.

2. Slope Detector

The slope detector is an electronic circuit designed to detect the presence of mouth alcohol as the breath is being captured by the machine. It does this by detecting any pronounced negative slope in the alcohol intake curve, since alcohol content from the mouth or throat will decline more rapidly than alcohol from the lungs. In theory, the presence of mouth alcohol will cause the test to abort. However, these "slope detectors" have proven to be inherently unreliable. The slope detector of this machine can be fooled by utilizing a slow, steady blow into the collection tube, thereby leading to an inaccurate result.


Reflux means that stomach acid and juices flow from the stomach back up into the tube that leads from the throat to the stomach (esophagus). This causes heartburn. Having heartburn two or more times a week is called GERD. Your test results from a breath testing machine will not be correct if you have GERD. In fact, you can be as low a 0.03% alcohol level, but the result on the breath testing machine may be in the ranges of 0.130 BAC (15% alcohol). This is because the breath testing machine measures the alveolar air from your lungs (deep lung air). If air from your stomach (reflux) is coming up into the mouth, then the result will be off. Although some breath testing machines are designed with slope detectors to measure the breath alcohol levels and to detect if there is alcohol coming from another source beside that of the lungs, such as the mouth or from the stomach in the form of a belch, empirical studies show the slope detector does not always work as advertised (see above). However, the problem with a person who has GERD is not that the machine is not working, but that the machine was never designed to detect this specific occurrence. Because a person with GERD has a constant flow of alcohol gas coming from the stomach into the mouth, unlike a belch which happens periodically and will spike the level of alcohol in the mouth, the slope detector does not detect that the air in the breath testing machine is deriving from two different areas. This is caused by the GERD fumes intermixing with the lower level of breath alcohol coming from the lungs due to actual blood alcohol level in the blood stream. The GERD fumes piggyback on top of the BAC coming from the lungs so that you get the combination of both alcohol numbers. A person that blows in the machine with GERD is combining the air from the lungs and the air from the stomach simultaneously which will can lead to a false-positive result.

4. Mouth Alcohol

Mouth alcohol refers to the presence of any alcohol in the mouth or airway during breath testing when the sample is given. If even a minuscule amount (not even visible to the naked eye) of raw alcohol exists during a breath test, then the result will be a false-positive reading. This is because the breath testing device assumes that the alcohol is from the deep part of the lungs (alveolar air). Therefore, even a microscopic amount of alcohol breathed directly into the machine from the mouth or throat instead of from the lungs can have a huge impact on the test result. Mouth alcohol is often caused by belching, burping (even "micro" burping), hiccuping, or vomiting within 20 minutes before taking the test which can bring vapor from alcoholic beverages still in the stomach up into the mouth and throat (similar to GERD noted above). If the machine reads a molecule of alcohol that is not representative of what is in the deep lung area, the result can be off approximately 2500 times!

5. Observation Error

The breath test operator who administers the taking of the sample is required in Texas to continuously observe the subject for at least 15 minutes prior to the sample. During the 15-minute observation period the subject shall be deprived of alcohol and any other foreign substances and shall not have regurgitated or vomited. The rationale behind this guideline is that the ingestion of alcohol or food, drinking, regurgitating, vomiting, or smoking within 15 minutes before giving the sample can possibly lead to an inaccurate reading. The need for an observation period by itself makes clear the concern with the potential for error with the slope detector. After all,if the slope detector detects mouth alcohol, why is it necessary to have a 15-minute observation period prior to administering the taking of the test?

Regardless, this observation period is not always followed by the operators. Often the ride to the police station is included in this period. As well, often only a sporadic or intermittent observation of the subject is conducted before the test. Failing to follow proper protocol with the observation period can lead to an inaccurate reading.

6. Interferents

Some natural and volatile interfering compounds do exist which can skew results. The machine fails to identify ethanol to the exclusion of all other chemical compounds, such as toluene. In other words, the machine can mistake other compounds for alcohol. A number of studies have shown that many substances can interfere with the infrared testing device that is not picked up by the instrument. Industrial compounds such as paint, glue, gasoline, thinners, and other compounds contain the methyl group (toluene) which the Intoxilyzer mistakenly will detect as alcohol concentration. Simply absorbing these products through your skin or inhaling the fumes can result in significant levels of the chemical in your body for hours or even days. If a breath sample is given with these products still in your system, it can lead to a false-positive result.

7. Radio Frequency Interference (RFI)

It is widely known that Radio Frequency Interference (RFI) can cause distortions in some types of breath testing machines, including the Intoxilyzer 5000. It is the same concept for why on an airplane the flight crew asks that you turn off all electronic devices, including cell phones and laptops. Many police departments provide this as a general rule because it is a real and viable concern. However, shockingly enough many breath test operators (or others in the same room while the sample is given) blatantly disregard this mandate and leave on their police radios. Article here.

8. Accuracy

The technical supervisor for each Intoxilyzer 5000 tests the machine by using a known reference solution that contains an alcohol concentration of a 0.08. The machine is then calibrated based on this known reference sample to check to see if working properly. The tolerance of the reference sample is plus or minus 0.01 based on the machine's reading. This means that any sample will have a given variance of at least 10%, which can be quite relevant in breath test cases at or around the 0.08 level. The Intoxilyzer 5000 has an accepted 0.010 margin of error, plus or minus 10% of the result. This can be quite relevant in very close breath test cases, especially where the state attempts to perform a retrograde extrapolation.

9. Margin of Error

The Intoxilyzer 5000 allows for a variance of 0.20 between the 2 breath samples obtained. For example, if a subject blew a 0.099 and a 0.079 the machine considers itself to be within acceptable parameters of accuracy. A 20% variance rate to be considered within parameters is not very accurate, and would only be considered accurate by a governmental agency. This can also be quite relevant in breath test cases where the state attempts to perform a retrograde extrapolation.

10. Testing During Absorptive Phase

Absorption of alcohol continues for anywhere from 20 minutes (on an empty stomach) to 2.5 hours (on a full stomach) after the last drink. Peak absorption generally occurs within an hour. A major problem with the results of the Intoxilyzer 5000 is that it measures what your breath alcohol content is at the time of the test, and not while you were driving. A person who has been drinking is either in the process of absorption or elimination. During absorption one's alcohol concentration is generally increasing. During elimination ones alcohol concentration is generally decreasing. Without knowing the time, manner, type, and physical characteristics of the subject and the exact drinking pattern, there is an equal probability that the alcohol concentration prior to testing (the time of driving) is higher, lower, or even the same as at testing. Simply put, there is the possibility that the BAC of the accused has risen from the time of driving to the time the sample is given. Again, this can be relevant in retrograde extrapolation cases, in that it is possible that the BAC was lower than a 0.08 at the time of driving given the absorption of alcohol to the time of the sample.

11. Breathing Patterns

Different breathing techniques and patterns can effect results significantly. Experts have indicated that breathing patterns can affect the breath test result by up to 30% or more. Most operators know this, and therefore can manipulate the samples by encouraging subjects to blow commensurate with the level of the previous sample. Dr. Micheal Hlastala, Professor of Physiology, Biophysics and Medicine at the University of Washington, concluded:

"By far, the most overlooked error in breath testing for alcohol is the pattern of breathing….The concentration of alcohol changes considerably during the breath…The first part of the breath, after discarding the dead space, has an alcohol concentration much lower than the equivalent BAC. Whereas, the last part of the breath has an alcohol concentration that is much higher than the equivalent BAC. The last part of the breath can be over 50% above the alcohol level….Thus, a breath tester reading of 0.14% taken from the last part of the breath may indicate that the blood level is only 0.09%."

12. Temperature

The Intoxilyzer 5000 operates on the principle that the measured breath sample has a temperature of 34ºC Changes or differences in body temperature from the "average" of 98.6ºF (or 37ºC with 34ºC for expired breath from the lungs through the mouth) will affect the test. A 1ºC change in body temperature can have a 6% affect on the test. Elevated breath temperature can have a critical impact on the accuracy of the breath test (possibly caused by fever, hot tub, sauna, detention in hot sun, back of patrol car in summer, dancing, menstrual cycle, etc.). As stated before, a variation of only 1º may result in a BAC reading that is 6% higher.

13. Hematocrit Levels

The hematocrit represents the fraction of whole blood composed of red cells and is correlated with the aqueous content of blood. The higher the hematocrit, the lower the concentration of water in blood, and vice versa. The average hematocrit for normal, healthy males is 47%, with a range of 40-54%; for females the average is 42% and the range is 36-47%. Since ethanol dissolves almost entirely in the aqueous component of blood, two individuals with identical actual BAC's but with different hematocrits would be expected to produce different breath test results. The person with the higher hematocrit, and therefore lower blood-water content, would necessarily be characterized by a higher concentration of ethanol in the aqueous component of his/her blood and consequently, by a higher breath test reading. Given that the Intoxilyzer 5000 uses only one partition ratio, experts have predicted that the normal variation in hematocrit can produce errors in breath test results in the 10 to 14% range.

14. Maintenance/Calibration

The Intoxilyzer 5000 is just like any other machine. Updates have to made, and parts repaired. If these things are not done correctly or in a timely fashion, it could possibly lead to a false-positive result.

15. Operator/Technical Supervisor Manipulation

The Breath Test Operator can have a very significant effect on breath test results. The operators look at stars on the machine to determine whether a sufficient sample has been given. Therefore, to ensure that the second test complies with the first, the operator can simply instruct the defendant to stop, or blow harder, until the results are identical (or within the .02 range). As well, technical supervisors have to maintain the machine to keep it working properly. A prime example where manipulation resulted in many invalid breath tests is demonstrated by the more than 1200 convictions overturned in Harris County in October 2009. Article here.

16. Incomplete Purging

The machine's sample chamber should be purged completely before each test. Therefore, an incomplete purging cycle during the machine's operation sequence can result in improper readings.

17. Ambient Air

Rooms where DWI suspects are routinely tested 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. In this example, the false-positive result could be attributed to the last subject, and not the current one.

18. Source Code

There have been some comparisons to the Intoxilyzer 5000 to the seemingly all-powerful Wizard of Oz, with some experts claiming that once they roll back the curtain, they're going to find that it is not the perfect machine they have made it out to be in the past. Many experts believe that the Intoxilyzer 5000 is simply an outdated contraption that should no longer be used.

The software known as the "source code" that actually calculates the number it reports is kept secret by CMI, the company that produces the Intoxilyzer 5000. The source code refers to the actual algorithm for the computer program that runs the breath testing equipment. The source code is written by a programmer in a high-level language that must be converted to object code (or machine language) before a computer can read or execute the program. What makes breath testing devices largely unique among other 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.

The questions posed by the mysterious source code are numerous. It is impossible to know "beyond a reasonable doubt" whether the mathematical equations employed by the Intoxilyzer 5000 have been properly formulated, calculated, and applied without intensive review and analysis. It is impossible to know for sure without further testing whether the source code has been subjected to the appropriate level of scientific scrutiny to be considered reliable. For something to be scientific, usually the overarching characteristic is that it must be peer-reviewed by others in the scientific community. In this case, the Intoxilyzer 5000 has not been, solely due to the manufacturers refusal to allow for this to be done. The answers to these questions govern whether or not it can be persuasively argued that the test results should be even be considered at all, on the basis that the state cannot guarantee that they are even reliable enough to sustain a criminal conviction.

19. ToxTrap

The ToxTrap is a device which can preserve a breath sample which costs roughly $2 to purchase. This would provide a definite way to retest a sample that a person disagrees with. Texas does not require breath test operators to use the ToxTraps, thereby denying the most effective way to re-evaluate a disputed result.

20. Warranty

The manufacturer of the Intoxilyzer 5000 provides no warranty for the Intoxilyzer 5000 for accurate and reliable breath testing. This is the warranty given with each Intoxilyzer sold

"CMI, Inc., a subsidiary of MPD, Inc., warrants that each new product will be free from defects in material and workmanship, under normal use and service, for a period of one year from the date of delivery to the first user-purchaser...."

"There are no other warranties expressed or implied, including but not limited to, any implied warranties of merchantability or fitness for a particular purpose..."

It seems ridiculous that CMI would warrant the machine for only one year, when they are commonly found in service at law enforcement agencies for sometimes ten years or more. CMI also says this machine is not warranted for any "particular purpose". This seems peculiar when, for the Intoxilyzer 5000, the "particular purpose" is measuring alcohol on the breath. So this, in effect, means they don't guarantee that it will measure breath alcohol. The warranty is a hotly debated topic among DWI defense attorneys, in that many find it hard to believe the state would base convictions on a machine that not even the maker of the product stands behind.