This has bothered me for a long time because I'm a software engineer. Virtually all software has bugs. The more complicated the software, the more bugs it has. Hardware's the same way. How do you know the breathalyzer worked properly? (Or the radar camera, for that matter?)
Well, one gentleman has fought this in Florida. As it turns out, though the machines are certified by the state, the judge was disturbed to find out that the state's breathalyzers electronics appeared different from machine to machine. The state argued that they can't turn over the software for the EPROMs (Electronic Programmable Read-Only Memory) because it's a trade secret. Well, that sucks. Because some company doesn't want their trade secrets turned over, you're not allowed to face your accuser. That struck the judge as unfair.
The judge has ordered that the source code and schematics of the breathalyzer be turned over to an expert witness (PDF). Only the expert witness can receive this information and he can't let anyone else see it. This is both good and bad. It's a small step in the right direction, but it does mean that every time someone is pulled over, if he or she can afford an expert witness, this process has to be repeated. Unless you're poor and can't obtain such a witness, of course.
It's going to be fascinating to see what comes of this. The state has fifteen days to provide the software. The state claims they don't have it. If the manufacturer won't turn it over, charges will be dropped. If the manufacturer does turn it over and the witness finds a defect, there's going to be hell to pay. Personally, I'm hoping for a defect. It's not that I want drunk drivers to get off. It's that I want society to start thinking about what it means for individuals to be accused by machines we're not allowed to interrogate. It's like being allowed to face our accuser but not being allowed to cross examine him.
Did the state certify all machines? What was their certification process? How often are the machines tested? How are the officers trained to use them? Will mouthwash set them off?
If machines are going to accuse you, their hardware and software should be open-source and widely available for anyone to look at and ensure that it's bug-free. Anything else is an offense to the Constitution. Claiming that a company's trade secrets trumps our right to face our accuser is disgusting. (Hear that, Diebold?)