Yes, it is possible to challenge breathalyzer results in your DUI case. It is possible in the same manner that it is also possible to challenge radar gun results in a speeding ticket case. However, in both instances, you must have good cause to challenge the readings.
There are several ways to challenge breathalyzer results. One of the most common ways is to challenge whether or not the police properly calibrated the machine at the time they administered the breathalyzer test to you.
Challenging breathalyzer calibration
Like all machines, breathalyzers will not function properly without maintenance. If the police did not calibrate the machine properly at the time they use it on you, then the court cannot trust the results of the test.
Usually, the police will provide testimony that somebody calibrated the breathalyzer prior to using it on you. If the police cannot provide this testimony, however, it is possible that the courts will throw out the evidence.
How does this happen?
Your defense attorney may subpoena the maintenance and calibration records of the particular machine used on you at the time of the DUI traffic stop. In the event that the officers did not properly calibrate the equipment, then the burden of proof goes back to the government.
Without breathalyzer results, it becomes much more difficult for the government to prove its case against you. At that point, the government will likely rely on proving your intoxication through other means. This may be through police officers testifying that they smelled alcohol on your breath, or witnesses stating that you were driving poorly at the time the police pulled you over.