commercial flight ( operator responsibility) or a private flight( PIC responsibility.)
Which regs or laws govern this? In the UK the
Air Navigation Order says the commander of an aircraft must be "satisfied that flight can be safely completed" (87). Therefore, as captain you must be satisfied that (for example) the baggage contains no dangerous material – so the captain of PA103, if it had been a UK-registered aircraft and he'd survived, would presumably have been technically culpable, just as the captain of a ship is culpable (in the navy, will be court-martialled) if his ship runs on a rock, even if he was asleep or on the can at the time and his first officer was on watch. But I don't see anything in the ANO that says you're responsible for illegal items – or illegal passengers, for that matter – so long as they're safe. Your country's mileage may vary.