Gooose, Peace back.
I know a couple of judges (golf, poker, parties) and they actually have quite a bit of latitude when interpreting the law in these misdemeanor cases. If it was a felony case, not so much, but even then, they can excercise their judgement to some extent.
If the email from the legal department of DFW was questioned, a simple phone call to the guy would confirm his interpretation. The legal department of DFW drafted the regs and their interpretation in a court of law will most definitely influence all but the most callous judge.
Other evidence would come into play. If the cop testifies that in his opinion,the guy was intending to snag a fish and had the snagging rig as evidence, you are toast. But if you have a 1'0 hook with small corky and yarn with a 24" leader, the cop would have a hard time trying to prove intent.
It seems that a lot of folks feel they can't win in a court of law. I've beaten some tickets, lost others. I've recently fought city hall and won. The courts and city councils are intimidating, but not totally unreasonable.
If you are guilty, ask for lenience, pay the fine and get on with your life. But if not, it is often best to pay a good lawyer for a brief consultation to give you the proper defensive stance so you don't argue irrelevant issues and waste the courts time and look like a nut.
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Timbermans motto: The only good tree is a log.