GETTING TO KNOW THE BAC DATAMASTER DMT --
"CHEMICAL" BREATH TEST
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| (image courtesy www.winbackyourlife.org) |
It is the chemical breath test device being used by all local police agencies in Ithaca, NY and Tompkins County. [The NY State Police use a different machine made by Draeger]. This machine doesn't actually use any chemicals in reading your breath--it uses light.
2. How does this machine work?
Most modern breath test machines use "infrared absorption spectrometry" to measure blood-alcohol concentration in the blood.
What is that? Basically, the police have you blow your breath into a heated tube and pass through a sample chamber. Then, an INFRARED LIGHT is shown through the sample chamber. If there is any alcohol on your breath, the infrared beam will attach to ethanol molecules and acetone molecules. Then, the machine reads HOW MUCH light passed through the chamber and generates a BAC percentage. (i.e. 0.08% BAC) If there is alcohol present in your breath, it will block some of the light...
3. What are the machine's limitations?
There are many...
a) The machine can give FALSE POSITIVE readings if the Infrared Light attaches to other non-alcohol molecules in your breath. Examples include, ketones (from Atkins type diets, vomit in your mouth, etc), stomach contents from your breath, dentures, recent dental work, esophageal reflux, pharyngeal reflux, and more. Anything in your mouth can skew the test and make it unreliable. Your body chemistry can also skew the result.
b) The machine assumes that all people are the same! The machine uses a "blood to breath conversion ratio" of 2100:1 milliliters. In words easier to understand, the machine relies on the premise that in EVERYONE the amount of alcohol in 2100 milliliters of breath equals the alcohol in 1 milliliter of blood.
Problem is --EVERYBODY IS DIFFERENT. The ratio doesn't take into account the following: gender, age, weight, medical history, and unique body chemistry.
In fact, members of the scientific community have said that the ratio varies in each person from 1100:1 all the way up to 3400:1. That's a HUGE range. But the machine only assumes 1 range for all people tested.
c) Even with the problems mentioned in a) and b) above --the test is still deemed admissible in NY. However, a defense attorney can argue the WEIGHT of the evidence (in other words, how important it is to a jury).
d) The Breath Test Operator (the police officer) has to follow all the right PROTOCOLS in giving the test. If any of the protocols aren't followed, then the test can be unreliable. The officer must observe the subject, check the subject's mouth for any contaminants or obstructions, and do proper checks of the machine itself (run a blank sample and a reference sample as well as make sure the machine is working properly).
--SUMMARY THOUGHTS--
The BAC DATAMASTER DMT is a machine that is far from perfect. Yes, it can read alcohol in people's breath --but it is designed to be rigid and fails to take into account that everybody is different.
In every DWI case, that's why it is critical to find a lawyer who understands the science behind the equipment...because the equipment can make mistakes.
P: 607-229-5184
BY: Attorney Mike Cyr
P: 607-229-5184
E: mike.ithacadwi@gmail.com
Twitter: @ithacadwi
