I feel obligated to weigh in on this one even though (obviously) I am for legalization. On each side here is a summary of common arguments as I understand them:
Those for legalization might argue primarily that the benefits of legalization outweigh the benefits of keeping it illegal. Primarily is the prison situation. Forget exact numbers for the moment and lets assume a very large percentage of the people in America’s prisons are populated with sellers and users of pot. Its an enormous drain on resources and has ruined countless lives.
Those that are in favor of keeping the status quo often cite that pot is a gateway drug which leads to use of harder drugs. In addition the damage that people who get high and wind up killing people in auto accidents and other situations will almost certainly go up after legalization.
Once these statements are made most arguments degrade into citing statistics and arguing the semantics which are, at best, half-baked guesswork (pun intended).
I try and stay out of that. I acknowledge that legalizing pot will cause its fair share of real, horrible problems. Kids will be more likely to try it. People will kill others in auto accidents. There will be people addicted to it who can’t stop. In short, it will be abused. However, in the case of marijuana, I still feel that a person’s right to get high should prevail. Its the same thinking that allows alcohol to be legal now and that is IMHO a far more dangerous drug.