This was actually discussed by the supreme court recently. the DEA busted a grower with 4 plants. Dude challenged the federal law on the grounds that the feds had no authority to enforce their law since, constitutionally, the feds can only enforce on issues of interstate commerce and things related as is specifically delegated to them in the constitution and all other matters are for the states to decide. Dude said that his weed was all personal and as such had nothing to do with interstate so the feds had no authority. The court ruled that even though the guy was using the weed personally and there was no interstate commerce involved in his specific case the feds were allowed to intervene because creating a supply of marijuana affected interstate commerce in weed even if the weed itself was not traded in this instance and furthermore the weed supply could in future be traded even thought there was no trading to date. Jacked up logic, i know, but the feds only had to prove that the guy's personal stash is could be related to the interstate trade of marijuana and that gives them all the authority they need to write and enforce retarded laws on the subject. If you want to change marijuana laws ya got ta go through congress, courts aren't gonna overrule anything for you, especially when its stacked with conservatives.