Any breathalyzer used in court without testimony of the administering officer or without the papers from the manufacturer of the breathalyzer certifying the source code isn't broken or buggy and provides sound results is automatically deemed a failalyzer
Counsel: Looks like we're not going to be able to take this to trial since a breathalyzers results are considered 100% accurate
Defendant: Yeah, but I only had one drink, and I wasn't even swerving very much. Are you sure those blood alcohol level results are accurate?
Counsel: Now that I think about it, the only guarantee I have is the manufacturers good will. I don't have any certifications as to the accuracy of the device or soundness of its source code and since we are in a court of a law, we must depend on legal documents; not simply the good will a business offers to its good customers.
Defendant: Yeah, we don't want a failalyzer in court
Counsel: We certainly don't