A few units of illegal items isn't really an issue. I personally ignore them, but you gotta remember that it's against the law so don't complain if you are told to drop them, although I do sympathise if you're blown to bits in such a scenario.
As for RP, why would any law abiding citizen or law enforcer bother talking to a criminal? If they're actively murdering people or smuggling Slaves and Cardamine...they deserve to be shot with no prior warning. That's how I play it and I reserve no regrets for doing so. If I encounter pirates holding up a lane, I'm not going to waste my time on the comms, I'll be ready to fire my weapons without giving them a chance to either return the favour or flee for their lives. I have even hired a mercenary to assist me in destroying two pirates trains with a full load of Cardamine, whilst another got away. There was no warning, they were ambushed on a lane and terminated there & then. Why? Because such a smuggling operation is a massive threat to Sirius, it results in a vicious cycle. Therefore, any talking should be limited to diplomatic measures between the relevant houses.