The author of "The History of England", Thomas Babington Macaulay was speaking about copyright when he wrote these words about the peril of enacting and attempting to enforce laws that will not be obeyed. Although the topic is different, the relevance remains. As oratory (it was a speech given before the British House of Commons) it is an exemplar of an ideal in form, logic and art. As an author himself, he was arguing against his personal financial interests. It was 1841.
. . . Sir, of the kindness with which the House has listened to me, that I will not detain you longer. I will only say this, that if the measure before us should pass, and should produce one tenth part of the evil which it is calculated to produce, and which I fully expect it to produce, there will soon be a remedy, though of a very objectionable kind. Just as the absurd Acts which prohibited the sale of game were virtually repealed by the poacher, just as many absurd revenue Acts have been virtually repealed by the smuggler, so will this law be virtually repealed by piratical booksellers.
At present the holder of copyright has the public feeling on his side. Those who invade copyright are regarded as knaves who take the bread out of the mouths of deserving men. Everybody is well pleased to see them restrained by the law, and compelled to refund their ill-gotten gains. No tradesman of good repute will have anything to do with such disgraceful transactions. Pass this law: and that feeling is at an end. Men very different from the present race of piratical booksellers will soon infringe this intolerable monopoly. Great masses of capital will be constantly employed in the violation of the law. Every art will be employed to evade legal pursuit; and the whole nation will be in the plot. On which side indeed should the public sympathy be when the question is whether some book as popular as “Robinson Crusoe” or the “Pilgrim’s Progress” shall be in every cottage, or whether it shall be confined to the libraries of the rich for the advantage of the great-grandson of a bookseller who, a hundred years before, drove a hard bargain for the copyright with the author when in great distress? Remember too that, when once it ceases to be considered as wrong and discreditable to invade literary property, no person can say where the invasion will stop. The public seldom makes nice distinctions. The wholesome copyright which now exists will share in the disgrace and danger of the new copyright which you are about to create. And you will find that, in attempting to impose unreasonable restraints on the reprinting of the works of the dead, you have, to a great extent, annulled those restraints which now prevent men from pillaging and defrauding the living.
The speech is worth study in and of itself, and well cited. It is obviously not about marijuana, but it relevant in that it makes the case that laws that will not be obeyed build a wall between society and the enforcers of the law; that the party in power is constantly in peril of introducing through their success the downfall of the spirit of cooperation essential to civilization.
Also, it is in this day an example of how a legislator should comport himself. This is what lawmakers used to be. You can read the whole of it here, since it is now in the public domain:
http://www.thepublicdomain.org/2014/07/24/macaulay-on-copyright/