I always run high beams during the day, but during the night I run low beams when there are oncoming cars or if I am about 500ft ft or so behind someone. (even though the law says closer is ok) I hate getting blinded at night myself, so I try not to do it to others. It can be dangerous, since you can't see as effectively when you have high beams blinding you.
That being said, I do think that he should have let you off with a warning. That would have been the decent thing to do, since it sounds like you were not aware of the law at the time. But unfortunately for you, from your exerpts, the law states that when he passed you, you should have gone to low beams as he was within the 300ft limit. So technically he was within the law to issue you the citation. Maybe he was having a bad day and took it out on you. Either way, I think it is going to be tough if you are planning to fight it.
Especially since it only takes a sec or so to switch your high beams off and you said he was going about 85, and even assuming you were going 55 mph, that would put him traveling at 44 fps faster than you. That means that it would take him 6.8 seconds to get out of the 300 ft minimum. Which is plenty of time to switch down to low beams. And it is even longer than that if you were going over 55. It sounds like your instructor did you a disservice if he told you to run your high beams all of the time at night. That is not safer, it could blind an oncoming driver and he could end up in your lane. My
