He's gonna get a fine for littering. That's it.
Not sure why a lawyer is needed. That's my point. And I'm guessing he'd settle right now for a meaningless amount and be done with it. If he wasn't in the wrong, the cop wouldn't have given him a citation. He even admitted, "I screwed up." It sucks, I don't blame him for doing what he did, fwiw.
I don't know the local code there, the local laws. What I do know, however, is that a $25 (or even $50) fine is oft times the easy out.
How much time is it worth fighting it? My time is worth more than $50/hour. Some will argue, "well, it's the principle of the matter." Alright, fine. What's that worth? $300? $500? $1000? More?
Just state your case to the judge, express your frustrations, and this most likely will end up mattering nothing in the end. Don't make mountains out of molehills.