"So the purpose of the law is social engineering?"Of course. One of the central planks of modern drug prohibition stems from a collectivist viewpoint: Namely, that your individual rights are not as important as your contributions to society, and so something that potentially cheapens the quality of your contributions should not be allowed, because your primary duty is to serve the whole.These people believe that you should not be allowed to do something that a weak mind could get potentially dependent on, because you might contribute less to society in the form of diligent work.Drug laws are just yet another example of Statism trumping individualism, of social servitude trumping personal liberty.It also helps generate and perpetuate a caste system. Getting caught gives you a criminal record, and most jobs background check. This serves to create a social divide between statist types who blindly follow all the rules, and freethinking, rebellious types who ignore laws they deem to be unjust.Basically, it's designed to reward the people loyal to the state, and punish/weed out dissenters who are willing to question their superiors.