Marijuana should be a legal, regulated substance, similar to the likes of tobacco and alcohol. The government for far too long has drilled the idea into the American peoples' brain that marijuana is a deadly, harmful, addictive substance. Because of the lack of education on marijuana, most people do not understand what marijuana really is, or what the effects from it are.
The government classifies marijuana as a "Schedule I drug", meaning it has no kind of medicinal value whatsoever. Oddly enough, the government has a patent on a chemical that is found in marijuana! Check it out for yourself https://www.google.com/patents/US6630507.
Legalizing marijuana can have an extremely positive impact for the American people, and is more than just putting another substance on the market.