Roadside breath tests not a reliable detector of drunkenness

Studies indicated that breath test device readings used by officers may have inaccurate and unreliable results, which may lead to a wrongful DWI charge.

Colorado law enforcement officers pull drivers over on suspicion of drunk driving on a regular basis. While some drunk drivers are obviously guilty of driving while intoxicated, others may be more difficult to determine whether they are driving with a blood alcohol content that is over the legal limit of 0.08 percent. In some cases, officers may use roadside breath test devices, which are designed to detect the presence of alcohol in a person's breath sample. If the breath test reading indicates that the driver has a BAC that is over the legal limit, they may be arrested and charged with a DWI. Many studies show, however, that roadside breath test analyzers provide inaccurate results when it comes to BAC levels and actual drunkenness.

One study conducted by the State University of New York at Potsdam found that one in four people tested had breath test device readings that were higher than their actual blood alcohol level. In some cases, the breath test results differed from the BAC results obtained from an actual blood test by at least 15 percent. Although these statistics may not seem significant, they could result in a wrongful DUI charge.

Breath test devices vs. blood tests

Both breath test devices and blood tests give officers a blood alcohol content level. Yet the route by which they obtain this information is quite different. After a person drinks, a percentage of the ethyl alcohol diffuses into the person's air as the blood passes through the lungs, according to How Things Work. When the air is exhaled, the breath test measures that percentage of alcohol. Blood tests, on the other hand, obtain BAC levels by directly measuring the amount of alcohol found in the blood. Research shows that the results obtained by these two methods are not comparable, and therefore, are not reliable.

Factors that can sway breath test device results

According to the State University of New York at Potsdam, there are several things that can cause a breath test reading to be unreliable. These include:

  • Fumes from gasoline, spray paint, paint thinner or cleaners
  • Electrical interference from police radios and cellphones
  • Traces of food, blood or vomit found in the subject's mouth
  • Dirt, smoke and other pollutants found in the air
  • The relative humidity and ambient air temperature

There can also be circumstances when an officer misuses a breath test device or the device has not been calibrated properly. All of these factors can increase the unreliability of a breath test reading.

Defending your rights

A DWI can affect your life in many ways. Not only can a DWI conviction make it difficult to find employment in certain industries, but it can affect your ability to qualify for a professional license or loan in Colorado. DWI charges should not be taken lightly. If you have been charged with drunk driving, you may want to partner with an established criminal defense attorney who may be helpful in answering your questions.