Police station “Breathalyzer” test results are often central pieces of evidence in DWI cases. Yet mounting evidence suggests they are not reliable.

New York has already ruled that portable breathalyzer test results aren’t admissible in court, but prosecutors continue to use the results of in-station testing.

This is problematic, since implied consent laws make it impossible to refuse either the portable or the station test without consequences. Your first refusal can mean a 1-year license suspension and a $500 fine. 

While the consequences of refusing a breathalyzer test are certainly less disruptive than a DWI conviction, they nevertheless push many people into taking the test who otherwise would refuse to do so. Some of them do so feeling fully confident they’ll get a negative result. 

According to a recent article in The New York Times, the devices “generate skewed results with alarming frequency, even though they are marketed as precise to the third decimal place.” The Times also notes judges in Massachusetts and New Jersey have thrown out more than 30,000 breath tests in the past 12 months alone due to human error. 

A good criminal lawyer can use this information to defend you from DWI charges. For example, calibration is a major reason why tests deliver incorrect results. 

There are also a number of medical conditions which can cause you to blow a false positive. For example, the keto diet can generate a false positive, because it releases isopropyl alcohol into your breath. While isopropyl alcohol isn’t the same thing as a beer, tests can’t always tell the difference.

They also can’t always tell the difference between blood alcohol and toothpaste, mouthwash, and breath mints.

Mistakes in the machine’s software can cause false positives as well. Software experts who have examined the machines say there are numerous flaws in the code which can cause false positives.

Breathalyzer tests aren’t the only inaccurate tests used to convict drivers. “Field sobriety tests” give the police grounds to arrest you, and prosecutors end up using the results of these tests as well.

Yet you can fail these tests simply because you’re too nervous to follow the instructions correctly, because a knee or foot injury keeps you from walking in a straight line, or for dozens of other reasons.

Even the blood alcohol tests which are touted as nearly perfect have issues. You can fail if you have diabetes, if you’re taking cough medicines, or if you’re taking certain herbal supplements. Human errors in the way the blood draw is conducted can also generate false positives.

Many people plead guilty to DWI charges because they believe the results of the tests used against them. They do so because they think they’re looking at scientific evidence of their own guilt that can’t be questioned.

If you’re in this situation, don’t take it lying down. Reach out to a tough criminal defense lawyer who will ask the right questions. A DWI charge can take your freedom, your career, your family, and your ability to move forward long after the potential jail time is done. You owe it to yourself to fight as hard as you can. 

See also:

Can I Get a DUI For Taking Benadryl?

Traffic Crimes in New York City

Your Rights in New York DUI Cases