Study finds marijuana not "safer" than alcohol

[Shoulders of Giants]

12. Alcohol is legal but marijuana is not.

Therefore, many of marijuana's consequences comes from it being illegal, not the drug itself. You could go to jail for using it or lose your job. While there are reasons alcohol would cause you to go to jail or lose your job, they are less likely. Marijuana being illegal also causes a self selection problem. People who would have done marijuana if it was legal, won't do it because it isn't. Therefore, people left doing marijuana are people who don't care as much about avoiding jail or having a good job that drug tests. Therefore, this is an unfair comparison. The only way to compare alcohol and marijuana fairly is to do it in a society where society treats both drugs the same. There is no society that does that, so its impossible to do a study like this. You cannot control for the societal acceptance of the drugs, because its impossible to tell exactly what impact that is.

However all that said, Alcohol itself appears to have a much worse impact on someone's health than marijuana. I don't recommend people do either, but this study seems very flawed. You just cannot do a apples to apples comparison of two activities economical and social consequences when one activity is legal and one is not. You would have to control for the variable of its legality, and I don't even know how thats possible for a study of this scope.