Five Ways a DUI Breathalyzer Can Be Wrong

Five Ways a DUI Breathalyzer Can Be Wrong

While drinking and driving is never a good idea, there are just way too many things that can go horribly wrong, people should also know enough information to protect themselves from a false reading during a breathalyzer test. The fact that there are a number of ways that a breathalyzer can be wrong during the testing process shows that the information these machines provide is not always reliable. This information can be used as a way innocent people can protect themselves against false prosecution of drunk driving.

Here are a five ways that a breathalyzer can be wrong.


Without regular calibration, many breathalyzers lose the ability to give accurate readings. The calibration process is meant to train the breathalyzer’s sensor so that it can detect accurately the amount of alcohol that is sent through the machine.

Residual Mouth Alcohol

It is important for those administering a breathalyzer test to observe a test subject for twenty or more minutes so that everyone involved that the test results are not thrown off because of any residual alcohol left in the subject’s mouth. The problem with testing a subject too soon is that the machinery assumes that any alcohol found in the breath of the subject comes from the lungs and therefore is a reading of how much alcohol is in the bloodstream. It is possible for a subject to have left over alcohol in their mouth that would give a false reading on a breathalyzer when their blood alcohol rate is not really over the legal limit.

Retrograde Extrapolation

One of the more common defense attorney strategies put in use to show the fallibility of a breathalyzer test is to put forth the strategy of retrograde extrapolation. Most breathalyzer tests take place at police headquarters, sometimes more than an hour after the traffic stop. What the theory of retrograde extrapolation attempts to prove is to backtrack from the time of the test to estimate what the true blood alcohol level was at the time of the citation, which would often be less.

Compound Interference

There are a number of compounds in existence that interfere with the results that a breathalyzer can come up with. It is known that those suffering from diabetes can sometimes have acetone levels that are so high that they can be read as being over the legal limit. Acetone is one of the compounds that breathalyzers falsely reads as alcohol. Other things that have sometimes shown to cause false positive readings in breathalyzer tests include inhalers and some dietary supplements.

Absorptive Phase Testing

It takes a given amount of time for alcohol to be absorbed into a person’s body, usually from half an hour to two or more hours. This is called the absorptive phase. Testing via breathalyzer during the absorptive phase can give a false reading because while alcohol is in the process of being absorbed it is not distributed evenly throughout the body.

Breathalyzers are something that anyone making the poor decision of getting behind the wheel after having more than a couple drinks will most likely have to deal with at some point in their life. There are a number of things that can go wrong though with a breathalyzer test, causing it to record false levels of alcohol in the test subject. It is important for those people being tested to know that breathalyzers are not infallible, and sometimes the mistakes that are made by the machinery or those operating them can cause someone to be falsely accused or even convicted of driving under the influence of alcohol