"And how would you propose to enforce such a thing? Once you make this legal the buying and trading of all supplies will be legal once more, the act will be easier, but we cannot be there at every summoning and every contract. We cannot intervene until after the act. You force us to work in a way that involves closing the gate after the horse has bolted, instead of by prevention. However much you educate you cannot be sure people will listen."

Even if you educate rules and warnings in a moment of emotion that can fall by the wayside. At least, Norrell thinks, if he outlaws it that makes the act itself more difficult to perform in a fit of passion.