Nevada Breathalyzers and Blood Alcohol Tests
 A "breathalyzer" is actually a specific brand of breath-testing machine, but for historical reasons it has come to refer to any of a growing number of brands and models — much as "Xerox" and "Kleenex" have also become generic terms. In fact, the breath machine used in Las Vegas DUI cases after arrest will probably be an Intoxilyzer 5000. To confuse things a bit more, some officers will ask you to breath into a small, handheld device in the field before you are arrested. These are called RBT (roadside breath tests) or PAS (preliminary or portable alcohol screening) devices; although they will give a blood-alcohol reading, they are generally not admissible in Clark County Courts — and you are not legally required to take them. The portable roadside device used in Las Vegas DUI cases will probably be the Intoximeter Alco-Sensor IV (RBT IV).
There are many problems with the way breathalyzers used in Las Vegas and throughout Nevada analyze your breath. These tests can be very unreliable and susceptible to attack by an experienced Las Vegas DUI lawyer who understands their weaknesses.
One of the major defects in many methods of breath alcohol analysis is the failure to identify ethanol (also referred to as ethyl alcohol) to the exclusion of all other chemical compounds. To use the terminology of scientists, such methods are non-specific — that is, they are not specific for ethyl alcohol: They will detect other compounds as well, falsely identifying any of them as "alcohol". Thus a client with other compounds in his blood or breath may have a high "blood-alcohol" reading with little or no actual ethanol in his body.
This problem of nonspecificity is most noticeable in the use of infrared breath analyzing instruments (the most popular type of breath testing machines used today). The technical reason for this lack of specificity is that most breath machines are 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 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 breathalyzer assumes that the methyl group is a part of an ethyl alcohol compound.
The simple fact is that there are thousands of compounds that contain the methyl group. Acetone and acetaldehyde, for example, can be found on the human breath. In fact, recent studies have found that over one hundred chemical compounds can be found on the breath. More important, approximately 70 to 80 percent of these compounds contain methyl groups. And the infrared breath machine will detect each of these as "ethyl alcohol".
How prevalent are chemicals in the breath that can register on breath analyzing machines? Here are some common things that can give falsely high readings:
- Inhaling Paint and Glue Fumes
- Inhaling Lacquer Fumes
- Swallowing Unleaded Gasoline
- Bread Products of various types
- Untreated Diabetics
- Persons on a Weight Reduction Diet
- Fasting
- Alcoholics can have 5 to 55 times higher levels of acetaldehyde in their breath or blood than that in nonalcoholics.
- Long-term smokers are more likely to have higher blood-alcohol readings due to a greater amount of acetaldehyde in the lungs.
Another major source of error in breath-alcohol testing is a design defect: the machines falsely assume that the individual tested is perfectly average in certain critical physiological traits. For example, all breath testing machines used in Nevada, including in Las Vegas, depend on the assumption that the ratio between alcohol in the exhaled breath and alcohol in the blood is 1 to 2100. In fact, the machine is designed to produce a reading based on that assumption; the accuracy of the reading is directly tied to the accuracy of the presumption. The actual ratio in any given individual can vary from 1:1300 to 1:3000, or even more widely. Thus a person with a true blood-alcohol level of .07 but a breath-to-blood ratio of 1:1500 would have a .10 reading on an "accurate" breath testing instrument.
For this and many other reasons, blood and breath tests can be effectively handled by a knowledgeable and experienced firm of Las Vegas attorneys specializing in DUI defense.
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