Nobody's going to sanction you for entering Liberty illegally. If that were the case, pirates would not exist.
If a member of the Navy spots you, they'll ask you to leave and escort you out. If you fail to comply, they'll shoot you. But that's all within RP and should be taken as such. As the respected central lawful authority, what's decided among them is generally what goes.
But that is not outside the boundaries of the playerbase. I'm a devoted Junker player. I can't hang around in public in Kusari, regardless of if I'm actually doing anything wrong. The mercs in Liberty thing is pretty much along the same lines.