Game wardens scare me more than cops.
They CAN look in your cooler if you have fishing gear, to enforce size limits. It's why I'm afraid of taking fishing equipment along as a disguise when planting outdoor crops. And I ALWAYS buy a license... f'real, where do you think the $$$ for management of the fish stocks comes from? (I used to work at a hatchery and take that shit kinda seriously)
They are usually a scary combination of good woodsmen with good educations and past military experience. REad: They will tap you on the shoulder before you even know they had been standing there, and you can't fool them, period.
Anyway good luck in court and please tell your buddy to buy a damned license next time! I honestly would not be surprised if the warden would have let you go and just confiscated your shit if you'd both been fishing legally.