According to Mantua's law the sale of deadly drugs was punishable by death.
Explanation:
When Romeo is looking for poison and knocks on the door of his Apothecary to get some for himself saying he needs a 'dram of poison' he is told by the understandably afraid Apothecary that even though he has it as all in the profession do, he cannot administer to Romeo as it would not end well for him either.
According to Mantua's law any person with the lawful possession of deadly drugs cannot sell them to any person at any circumstance and only administer them for health.
