If the police charge you with a DUI, it is highly likely that a vital component of the evidence is breathalyzer results. However, just like you can challenge the radar gun results when you get a speeding ticket, it is also possible in some situations to challenge breathalyzer readings.
How successful a breathalyzer challenge will be depends on your case specifics. According to FindLaw, the most common ways to challenge breathalyzer results include challenging the reliability of the machine itself or challenging the officer’s ability to give a breathalyzer exam.
Breathalyzers are machines. Just like any machine, it is possible for a breathalyzer to be faulty. For example, in one specific DUI case in Iowa, a man was able to blow a high reading on a breathalyzer the police were using even though he was completely sober in court. This invalidated the results.
Additionally, even if a breathalyzer is functioning correctly, it must be properly calibrated before the police can use it. Usually, the prosecution will provide testimony to prove this. However, if the prosecution cannot provide this the court will throw the breathalyzer results out.
Police training and illegal searches
Just like with a speed radar gun, a police officer must have training with breathalyzer machines. If the officer who gave you the breathalyzer exam lacked this training, the courts cannot accept the results.
Additionally, the police officer must have had probable cause to administer a breathalyzer exam to you. Again, usually the prosecution will provide testimony that you were exhibiting signs of intoxication at the time the officer administered the exam. If this testimony does not exist, the breathalyzer’s use was illegal.