If I were you, I'd also make comparisons towards alcohol prohibition and the costs, both socially and economically, that prohibition brought on the nation in conjunction with the incredible amount of money that's spent in a futile effort to "prohibit" marijuana usage.
In addition, mention how criminalization has no effect on the available supply of marijuana, it merely inflates the prices substantially while de-legitimizing what could otherwise be a legitimate business like the sale of hard liquor or ciggerettes..
Try and give mention how removing the sale of marijuana from reasonable business and health regulations by criminalizing the drug only encourages individuals who don't consent to the laws in the first place to engage in an illegitimate black market, substantially increasing the available profits to be made from the drug while increasing the danger and risk that takes place with each transaction.

Discuss the costs of trying to house nonviolent marijuana offenders in prisons, and the toll that this takes on society in comparison with the entirely benign effects of marijuana.

If you really want your paper to be easy, just by the book [I]Why Marijuana Should Be Legal.[I] It's by Ed Rosenthal & Steve Kubby, it's about 11.95 and will contain just about all that you need to know for your paper.