"For most of human history, marijuana has been completely legal. It's not a recently discovered plant, nor is it a long-standing law. Marijuana has been illegal for less than 1% of the time that it's been in use. Its known uses go back further than 7,000 B.C. and it was legal as recently as when Ronald Reagan was a boy.
The marijuana (hemp) plant, of course, has an incredible number of uses. The earliest known woven fabric was apparently of hemp, and over the centuries the plant was used for food, incense, cloth, rope, and much more. This adds to some of the confusion over its introduction in the United States, as the plant was well known from the early 1600's, but did not reach public awareness as a recreational drug until the early 1900's."
Taken from
http://blogs.salon.com/0002762/stories/2003/12/22/whyIsMarijuanaIllegal.html
Alchahol actualy does more damage to the human body then marajuana, and it's more addictive then marajuana,
plus if we legalize it, we would also legalize hemp, which is an extremely durable fiber that has a huge number of uses.
Such as, a food that is a great sorce of protein, minerals, and dietary fibre.
Paper, which would save a lot of trees etc.
"REFUSING TO GROW HEMP in America during the 17th, 18th and 19th Centuries WAS AGAINST THE LAW! You could be jailed in Virginia for refusing to grow hemp from 1763 to 1769; Hemp in Colonial Virginia, G. M. Herdon."
Quoted from:
http://www.venusproject.com/ethics_in_action/Real_Reason_Hemp_Illegal.html
Plus one of the only reasons that it is illegal is because of a smear campaign against hemp that a few farmers made out of fear....