How accurate is a breathalyzer test?
Driving under the influence, also known as DUI, is an offense that is most commonly supported by the results of a blood alcohol test or a breath alcohol sample. Most people refer to the instrument that measures breath alcohol levels as a Breathalyzer. However, what most people do not know is that the Breathalyzer is simply just one of the three major versions of breath alcohol testing devices. These devices are called: the Breathalyzer, the Intoxilyzer, and the Alco-sensor.
In general, the Breathalyzer is a device that uses a series of chemical reactions to measure the breath of the suspect. A Breathalyzer has two glass vials containing a chemical mixture that first, separates the alcohol from the air. Then, the sample goes through another reaction which causes the reddish-orange liquid in the vial to turn into a green color. The degree of the color change is correlated to the level of alcohol in the breath sample. Another kind of breath alcohol testing device is known as the Intoxilyzer. The Intoxilyzer uses infrared spectroscopy to detect alcohol. Infrared spectroscopy identifies molecules based on the way they absorb infrared light. Furthermore, molecules are constantly vibrating. These vibrations change when the molecules absorb infrared light. These absorbed wavelengths help to identify the substance, while the amount of absorption tells you how much of the substance is present. The Alco-sensor is the third type of device that is used to measure breath alcohol levels. The Alco-sensor uses modern fuel-cell technology which relies on a series of electrodes and porous electrolyte materials that flow through a wire. This wire is connected to an electrode and a meter that measures the electrical current. The more alcohol that oxidizes in this process, will create a greater electrical current. This electrical current is measured by a microprocessor which also calculates the amount of alcohol present in that breath sample. Overall, these are brief descriptions of the three devices that are used to measure breath alcohol content.
In the State of Florida, when you're accused of driving under the influence, the standard instrument that you use is no longer the breathalyzer, although that's what it's commonly referred to. It's actually called the Intoxilyzer 8000. No one can really tell you with any degree of scientific certainty how reliable or accurate these machines are. The State and some of their agents have gone through great length and expense of protecting that information. Some very competent lawyers, well before my time, had litigated heavily to try and gain access to it and generally speaking, it was an unsuccessful effort.
We're left with this shroud of uncertainty. But there's a benefit to that because now, at trial, if you proceed that way, you can explain that uncertainty to the jury. You don't need to just take the Intoxilyzer result at face value. They can be challenged. And frankly, the burden is on the government to prove their case. Never the defense. If the government doesn't even know how it works, how can the jury?
It's really important to have that appreciation. The lawyers in our office can explain that to you. It's such a relief, in fact, you see the relief wash over clients faces often times when we really get into the particulars, and they realize, "You know what? This breath reading might even be junk science." If you call our office to discuss your case, these are the types of things we'll go over with you.