All drugs should be legal, in keeping with the libertarian principle of freedom to do as you please as long as you are not being responsible for harming others. If you think that it is personally immoral to do drugs, that’s fine and that’s not the point. The question is about legality. For example, I think it is immoral to gossip negatively about people behind their backs, but I don’t think that this should be against the law. And, you might say that drugged people sometimes do harm others, justifying illegalization. But, in whatever way a drug user may be responsible for the harm of another person, let that act be illegal, not the drug itself. For example, if a drugged person shoots and kills someone, then this act is already illegal because murder is illegal. But, using a drug does not necessarily mean that a person will go out and harm someone, as there are many peaceful drug users who just hang out in their living rooms. Similarly, even though some people harm others under the influence of alcohol, that doesn’t mean that alcohol itself should be illegal, but only the harmful acts.
Besides that moral argument of freedom, outlawing drugs has terrible effects on many people, mostly the poor and black. It forces the market underground where it becomes more violent. If you hate organized crime and drug lords, then you should legalize drugs, because outlawing drugs eliminates legal competition and pushes the market toward the organized professional criminals, just like in the days of alcohol prohibition. Criminalization of drug use also puts many, many black and poor people into jail, destroying the black community and families, making it difficult for those caught to get a future job, and so increasing poverty. Incarceration usually breeds future incarceration. Most people who go to jail once then go to jail again. Those in jail for drug use then have a decent chance of becoming more hardened violent criminals in the future. The U.S. actually has the highest prison rate (that is, percentage of people in prison) in the world, mainly because of the drug war. By the way, it’s extremely expensive to the government to find, prosecute, and imprison a person. If we legalize drugs, then we can help many people climb out of poverty, help poor and black families, reduce real crime (besides the “crime” of drug use), and save a lot of tax money. The government is the enemy of the poor and black.