I don't usually agree with Rand Paul but I agree with him on this. Marijuana use is but one of many things, that while not positive, shouldn't be a federal crime. Regarding marijuana users Mr. Paul stated "... I don't want to put them in jail and ruin their lives." A sentiment I agree with 100%.
http://www.huffingtonpost.com/2013/03/24/rand-paul-marijuana_n_2945307.html
http://www.huffingtonpost.com/2013/03/24/rand-paul-marijuana_n_2945307.html