If you are dealing with DUI charges, it is highly likely that your case will hinge on breathalyzer results. Not all DUI cases do, but most of the time the prosecution will start off with what the breathalyzer results say.
Just like it is possible to challenge a radar gun in a speeding ticket trial, it is also possible to challenge breathalyzer results in certain circumstances. According to FindLaw, if you wish to challenge breathalyzer results, you will either need to challenge the reliability of the machine itself or that of the officer who performed the test.
In what ways can breathalyzers be unreliable?
Given that breathalyzers are machines, it is possible for a breathalyzer to be mechanically unreliable as a matter of course. For instance, in an Iowa case, a man was able to blow a “HI” reading on a breathalyzer while stone cold sober in court.
Even in the event that the machine itself is generally reliable, somebody must calibrate the machine before it can give good readings. Typically, the police will provide testimony that somebody calibrated the breathalyzer before use, but if the police cannot provide this testimony the court may throw out the evidence.
What might be wrong with the officer performing the test?
Just like with radar guns, police officers must be properly trained on using a breathalyzer. If the officer lacked this training, the court may deem the breathalyzer results unreliable. Additionally, the police must prove that the breathalyzer test was not part of an illegal search. The police must have had reasonable suspicion to pull you over for drunk driving and probable cause that you were drunk at the time.