DUI Breath Tests: How Accurate Are They?

On Behalf of | Nov 18, 2019 | DUI

You’re driving down the road and see the flashing red and blue lights behind you. You don’t think you’ve done anything wrong. Maybe your taillight is out. You pull over to the side of the road, and when the officer approaches your vehicle they ask if you’ve had anything to drink. Sure, you had a couple alcoholic beverages earlier, but not enough to impair your driving.

The officer asks you to blow in a portable breath test, which you do because, again, you aren’t drunk driving. Unfortunately, the machine registers your blood alcohol concentration (BAC) at .09%, which is above the legal limit. The officer arrests you and takes you down to the station.

While at the police station, you are asked to take another breath test, this time on a larger machine, which is supposed to be more accurate than the handheld device. Again, your BAC is measured at an unlawful level. You are charged with a DUI.

In America, this situation is common. A person is charged with, and sometimes convicted, of driving under the influence because a machine generated results that indicated that the person was intoxicated. The unfortunate thing is that some guilty verdicts in DUI cases could be based off inaccurate information.

A Report on the Reliability of Breath Analyzers

The New York Times recently released a report about the accuracy (or inaccuracy) of DUI breath test machines at police stations across the country. The reporters interviewed over 100 lawyers, scientists, executives, and police officers. They also scoured documents regarding the programming of these machines, as well as the reliability of their results.

The Times found that breath test machines frequently produced inaccurate results.

In some cases, the results were 40% higher than they should have been because of factors such as:

  • Human error
  • Poor calibration
  • Lax maintenance

Court Allows Experts to Examine Breath Analyzer Software

The New York Times reported that, in 2007, after defense attorneys attempted to get access to the programming side of breath test machines, the New Jersey Supreme Court ordered Dräger, the manufacturer the Alcotest 7110, to allow experts to examine the software. They found that it had many programming errors. The court said that, although the Alcotest 7110 was reliable overall, mechanical issues could produce inaccurate results.

Later, experts examined Dräger’s Alcotest 9510, and also came up with alarming findings. The programmers who looked at the machine wrote a 9-page report on their results, saying that it wasn’t sophisticated and could sometimes round up BAC levels.

Dräger asked the programmers not to share the report with others and to request those who had copies of it to destroy them. The company said it was protecting its intellectual property.

Results Breath Analyzer Examinations Increase Skepticism

According to The New York Times, results from studies such as the ones on Dräger’s machines, and the lack of proper upkeep, have made judges skeptical about the use of BAC levels as evidence in DUI cases. A county judge in Pennsylvania said that it was “extremely questionable as to whether or not any DUI prosecution which utilizes a reading from an Intoxilyzer 500EN breath testing device could presently withstand scrutiny…”

The New York Times reported that Massachusetts and New Jersey have invalidated results from over 30,000 breath tests in the past year.

Legal Requirement to Submit to Breath Tests

Although breath tests have the potential to generate skewed results, people arrested for driving under the influence are still required to take them. Sure, the individuals can refuse, but, technically, that’s illegal. Under Pennsylvania law, any person who operates a vehicle on state roads has given implied consent to be subject to one or more breath or blood tests.

If a person refuses to submit to a breath test, their driving privileges could be suspended for:

  • 12 months, or
  • 18 months if they previously:
    • Had their driver’s license suspended
    • Refused a breath test

Additionally, the law allows the results of breath tests to be admissible in court, which means you could be wrongly convicted based on evidence from a faulty device.

Schedule a Free Consultation with the Law Offices of William D. Thompson

If you were arrested for a DUI and agreed to submit to a breath test, you may be able to challenge the results. Based on The New York Times’ findings, several factors, such as human error, poor calibration, and lack of maintenance, could have skewed the BAC level.

At the Law Offices of William D. Thompson, we will thoroughly investigate your case to uncover weaknesses in the prosecution’s evidence.

We are committed to providing the dedicated legal defense you need in Scranton. Request a free consultation today by calling us at 570-846-2819 or contacting us online.