This is really a tough question because there are such good arguments that both support the legalization of drugs and support keeping the use of drugs illegal.
Keeping drugs illegal scares many people away from drugs. Just the mere thought of going to prison is enough to make most people steer away from them. The ramification of drug use carries the stigma that using drugs is wrong. On the other hand, legalizing drugs could put many (not all) drug dealers out of business (or it could make them lower their prices and drugs would be a whole lot cheaper).
Legalizing drugs could create money for the economy but I am afraid this could backfire in many horrible ways.
I think the legalization of drugs would be a bad idea. First, many people who advocate for this will probably never take drugs or have been taking drugs in a responsible way (at least they think so). For this reason, they may not see the ramifications of what drugs can do to others who are less able to resist. In other words, just because it works for some does not mean that it will work for others. A second point is that just because the laws are not working well now, this does not mean we should radically change things. Perhaps the laws are working well enough. We don't know the alternative; it could be far worse. Finally, if everyone agree that there is an alcohol problem, then think of the problems that could potentially take place by adding drugs.
I agree with Pohnpei that, while I dislike the effects of recreational and habitual drug use on our society, the laws against such drugs have been miserable failures. We have put 2 million people in prison over the past thirty years, with more than half of them being arrested on non-violent drug charges, with almost no impact on the rate or amount of drug use.
As with alcohol, legalization would allow the drugs to be taxed, their content to be regulated and controlled, and every criminal organization responsible for its distribution in the US would be out of business in one fell swoop. While it would surely not be that simple and legalization not without its own set of problems, I believe it would be better than what we have now.
I think we would be better off if all drugs were decriminalized and I say that as a person who has never and will never use drugs.
I think that the War on Drugs does not really do much to help the country. I think that having drugs be illegal essentially just glamorizes them. I also think that banning drugs while permitting and promoting alcohol is pretty hypocritical since both can ruin people's lives.
I think that decriminalization would actually reduce drug use and drug-related violence and I think that it would make it safer for the people who are foolish enough to use drugs to do so.
Round the world, in every country there are laws against many different activities classified as criminal activities by those laws. Still in all those countries those activities persist. So can we conclude that since the law is not able to totally eliminate those activities laws against those activities are ineffective and therefore should be abolished? I don't think that will be right. So, I do not thing that even the drug prohibition should be abolished because it is not 100 percent successful.
Similarly, we cannot say that criminal activities are criminal just because the law prohibits those activities, and when legal restriction on engaging in those activities are removed, the people indulging in those activities will behave more responsibly in interest of others and society. This is like saying that if thieves had no fear of being on the wrong side of law by stealing, they will steal in a way that cause less damage to the society. Similarly we cannot expect that abolition of drug prohibition will induce drug peddlers to voluntarily reduce the quantity of drugs they sell, or less people to become addicted to drugs, or the drug addicts to to consume less drugs. I do not see how lifting all ban on drugs will lead to reduction in drug consumption or its ill effects on people.
Some people consider prohibition on drugs and restriction on many other things as infringement on individual rights of free choice. But when a mother forces her baby to gulp a bitter medicine, is she infringing the right of free choice of the child. Fact is that not all people have the required knowledge, understanding and ability to act in their best interests, and all the laws in the society are designed to protect such interests of the people as they cannot do by themselves. If we justify removal of drugs prohibition on consideration of right to free choice, we may have to remove many other laws. For example, the law will then not be justify prohibiting duel between two people who mutually agree to fight it to settle some dispute between them.
Some people have never taken and perhaps will never take drugs even if it is freely available, just as some people are so careful that it is impossible to pick their pockets. This is no justification for either legalising drugs or pick-pocketing. There are many people who do take drugs, and there are many more who are likely to fall prey to it if drugs were available more freely. Prohibition against drugs is meant to protect such people who are vulnerable against drugs.
Again comparison between drugs and alcohol is not entirely justified. Just because in USA carrying of gun legal, it does not mean that people should be allowed to own, carry and use freely powerful automatic weapons.
One of the principal arguments against drugs is if one looks at the effects of alcohol, everything from traffic accidents to violent behavior, then legalizing drugs should only compound the problems. Any such effects would only create more traffic accidents, violent and criminal behavior, and other ill effects. I don't see drugs being decriminalized any time soon.
The effects of alcohol related instances are so devastating, costly, and time-consuming, there doesn't seem likely a chance that drugs will ever be legalized in the United States.