Prohibition and the draconian "reefer madness" attitude towards marijuana is a big reason why there is a dearth of peer-reviewed research.  

I assume you are aware that that the DEA decided to keep marijuana classified as a Schedule 1 drug last year, meaning that the major restrictions on marijuana research will remain right? You do know that it is marijuana's status as a Schedule 1 drug that has prevented research right? 

Maybe you should ask yourself why the DEA is so in favour of restricting research.