Breathalyzer Accuracy

You may not realize it, but breathalyzer tests are not always as accurate as they are claimed to be. Because breathalyzers are normalized around test results of the average individual, they can display readings that are quite off for people who do not fit the “average” mold.

Understanding how breath test machines work will help you realize why they are not precise and that it is more than possible to form an effective defense, even if your DUI charge is backed up by a breathalyzer reading.

How Breathalyzers Work

A breathalyzer is a machine that accepts a breath sample from the user and analyzes it to determine the amount of alcohol present in one’s body. In the state of Rhode Island, the most commonly used type of breathalyzer test is the Intoxilyzer 5000, which uses infrared (IR) spectroscopy to examine the input.

The breath sample, once taken into the machine, is held in an internal chamber. Here, an IR beam is passed through it and absorbed on the other side by a photocell. Since air with a higher alcohol content absorbs different amounts of light, one’s BAC level can be determined by measuring how much of the IR beam is absorbed by the photocell after it has passed through the breath sample.

Sources of Inaccuracy

Breathalyzers, though advanced technologies, do have inaccuracies in the way they function and process their readings. They measure the amount of alcohol in one’s breath, as opposed to one’s blood. Because of this, the reading must go through a conversion in order to determine the actual BAC level. The conversion factor used, however, is a number based on how the average individual’s BAC level relates to his or her breath alcohol content level.

Each person is different, however, and because of this, the breathalyzer test is often inaccurate.

Contact Us

If you would like to learn more about breathalyzer accuracy and how you can best defend your DUI charge, contact Rhode Island DUI defense lawyer James Powderly today at 401-662-9006.