Marijuana should be legal for medical purposes, and strictly regulated but legal for recreational use. Obviously, if it is used for medical purposes, it should be monitored just like other drugs of its class. I don't see it as being that different from alcohol for recreational use, but I still think it should be legal with strict regulations.
Sure, the stereotype of the lazy, junk-food-eating stoner is pervasive, but marijuana users are generally not doing anything too harmful to society. Alcohol, meanwhile, can make its users unpredictable, violent, and depressed. Recreational use, if moderate, of marijuana isn't anything that should frighten us as a nation, and decriminalizing it would have economic and legal advantages.
As someone who has never tried marijuana, there is absolutely no reason to establish it as against the law. Illegal, commonly use recreational drugs, alcohol and tobacco are far more damaging than marijuana. Scientific studies reveal that it is impossible to overdose on marijuana and it is not a significant impairment on psycho motor skills. Studies found that while it does slightly limit the user's response to emergency situations, the user compensated for their impairment and drove more carefully, while drivers under the influence on alcohol's drive in a reckless manner.
There are also significant benefits to legalizing marijuana. There is way too much money being spent incarcerating users of marijuana for use of such a trivial drug. The recent estimate is about ~400 million we could be saving. Additionally, Colorado recently legalized recreational marijuana and already made 184 million by February. They're estimated to make a billion by the end of the year. Nationwide legalization will mean significant economical benefit.
Drug use isn't a good thing. But prohibition is even worse. Prohibition is vastly more destructive to society as a whole than is drug addiction. Damaging drug use should be frowned upon and discouraged. When politicians make a substance illegal, what they are really doing is making some person who probably lacks scruples very rich. They are turning the helping institutions of law enforcement into damaging institutions.
Marijuana legalization is definitely the right thing to do in society. Currently, in the United States, marijuana is classified as a drug in the same ranks as cocaine or other serious drugs. It has been scientifically proven that marijuana cannot kill someone, as they cannot overdose. If alcohol can be legalized, which causes thousands of deaths per year, then marijuana should be as well. In addition to this, cigarettes smoking should be banned because it kills so many people per year.
Only medical should be legalized but should only be used in a hospital setting and if you are caught even outside the hospital doors stoned then yes you should be arrested. It should not be legalized for recreational use AT ALL as the drug can be very dangerous to the users and societies health.