Hey guys I have to leave Poland to come back to the states soon and I haven't paid a traffic ticket I got a few months back yet and plan on doing it later but I was wondering if they would stop me from leaving at the airport?
Yes. There's a high chance that you've been taken to court in absentia for not paying the ticket and there might very well be a warrant out for your arrest.
I wouldn't dare - I know that they used to pull people (pre-Schengen) for things like this on the land border, so it stands to reason that they would do it on the air border.
I doubt he'll have any problems if he just goes to the police station and asks to sort it out - a bigger fine, but no problems as such.
They will only stop you if there is a specific warrant issued. If there is, you may have to spend a little time locked up while they sort the paperwork. Remember that bureaucracy here is slow, inefficient and corrupt. If there is no warrant issued you will have no problem, even if the fine shows on their system against your passport.
I got a ticket some years ago while ignoring the pedestrian red light (streets were completely empty). Got fined 100 PLN, Did not pay, but they caught up with me when one year later my bank informed that they had to block my bank account on order of Warsaw City Administration unless I would pay.
In retrospect not fair, because so many crazies on the roads and nobody bothers them.