Law is complicated. No one has full knowledge of it. Even lawyers and judges need to look stuff up.

The Virginia Beach law lecturer with the great 'Don't talk to cops' video on youtube mentions that the federal government doesn't even know how much written law there is - they can't catalogue it all.

That's why police officers aren't Judge Dredd. It's really a character question whether a police officer subjects someone to defending themselves in a case like this, especially as part of a speeding ticket. Wait until there's an accident or something where it might play a role. That is, if they can keep their ego in check.

I'd like the principle to be that police should enforce the laws they know, and leave alone (or check) anything they're not sure about.

In this case I think it would've been most reasonable for the officer to ignore the fact that she was wearing Google Glass, and then check whether they should issue tickets for that in the future.

Or, instead of letting a "crime" skate by, he could let the judge decide whether it's illegal or not.

I don't think it was a matter of whether or not it was a crime per se, but that if it did fall afoul of the "monitor in view" law then it meant that there was a potential danger in its continued use.

It's not difficult to infer that the officer initially intended to issue a warning to the woman about wearing Glass while driving, and that she argued the point saying it was not illegal. Her argument definitely would've signaled her intent to continue driving while wearing Glass, which the officer would have construed as a potential safety risk.

The officer really had no choice in the matter at that point, I'd say.

There are a whole host of allowed monitor uses in cars, not the least that entire occupations are exempt from the law. From what I've read, the officer did not attempt to gather any information along those lines once they were challenged, they just decided to show her who's boss.

The point is that there was no law to be ignorant of, as there had been no precedent for whether or not Google Glass qualified as a "monitor in view".