On balance it is beneficial for the citizens of the United States to keep use of marijuana illegal

It seems I've been debating a few "angels" recently. Here's for a better debate than the last =) My opponent have agreed on all the terms. The moral framework I will be using is the non-agression principle. In short this principle states that all actions which do not commit an act of agression, that is a purposeful and direct harmful action, against someones property or person are permissable. My justification for this principle is the concept of argumentation ethics. When two parties are in conflict with one another, they can choose to resolve the conflict by engaging in violence, or engaging in argumentation. Thus, by choosing to resolve a conflict by argumentation the parties have implicitly rejected violence as a way to resolve their conflict. Non-violence is thus an underlying norm of argumentation, that is accepted by both parties. Because during argumentation both parties propound propositions, and because argumentation presupposes certain norms (as it is clear that when two parties are arguing, they have self-evidently come to the conclusion that discourse is preferable to violence when a disagreement is reached), the act of putting foward a proposition that negates the axiomatically agreed propositions of argumentation is a performative contradiction. That is, the action contradicts the axiomatically assumed principle. To argue that violence should be used to resolve conflicts is a performative contradiction. I will provide three main contentions this round; to make marijuana illegal is an act of agression, the harmful effects of marijuana are very limited, and the harmful effects of making marijuana illegal are significant. 1. Making marijuana illegal is an act of agression The most trivial argument first. Obviously to prevent someone using a drug such as marijuana is an act of aggression. Force must be used to prevent someone who wishes to use the drug, using it. By making marijuana illegal, the government is commiting to applying an aggressive penalty, (arrests, use prevention, fine or other sanctions) when the drug is used. This is definitionally an aggressive action. 2. Marijuana has very limited harmful effects. Marijuana is essentially harmless in terms of biological damage to ones body. So much so, that scientists have had difficulty, under lab conditions, overdosing rats. The discovered overdose level, on Merke index, in rats was 1270mg/kg. (http://www.erowid.org...) To put this in context, the average amount of THC (the primary psychoactive constituent of marijuana) in a joint is less than 10mg. One would have to smoke several thousand (assuming a body mass of about 60kg) joints in very short period of time to reach toxic levels of THC in the body. This is functionally impossible. According to a 2006 United Kingdom government report, using cannabis is much less dangerous than tobacco, prescription drugs, and alcohol in social harms, physical harm, and addiction. (http://news.bbc.co.uk...) In short marijuana is less harmful than hundreds of legal substances. Why should it be treated differently? 3. Harmful effects of making marijuana illegal - Cost A 2008 study by Harvard economist Jeffrey A. Miron has estimated that legalizing marijuana would save taxpayers $50.8 billion a year in the United States " $44.1 billion from law enforcement savings, and at least $6.7 billion from marijuana in tax revenue. (http://blogs.reuters.com...) - Cost of lives In the mexican drug war alone there have been over 125,000 casualties, 1000 of which have been children. http://en.wikipedia.org... - Black markets It is economically trivial demonstrate that banning something creates black markets. This creates a source of revenue for criminal gangs. - People imprisoned unjustly In short people using marijuana do not inherently harm others, they do not harm themselves and making marijuana illegal has vast awful unintended consequences on many people. Over to Pro