As you know, drug trafficking is a huge topic and you will need to narrow things down a bit. More specifically, you will need to have a strong and pointed thesis.
I think one interesting topic could be on the issue of legalizing drugs. I am certain that there will be many critics, which make this thesis even better. A good thesis is debatable. Also because there will be so many critics, you already have your body paragraphs. All you need to do is take their arguments one by one and refute them. The more cogently you refute these arguments, the better your paper will be.
Also I would add an economic twist. We are in hard economic times and the government needs more revenue. Taxing some drugs might be a good solution. This is just a thought.
Finally, you do not need to agree with this thesis; all you are doing is writing an argumentative paper. Good luck.