Marijuana Prosecution Not a High Priority, Says Obama +>Marijuana Prosecution a Political Priority, Says Obama. In swing states, or 'potential' swing states the feds won't ruffle any feathers - It's cool man. In California, which is not in play, the feds will hammer you.
Second issue (without regard to anyones position on either topic) - contrast the federal approach to say, the Arizona immigration law with:
"It does not make sense from a prioritization point of view for us to focus on recreational drug users in a state that has already said that, under state law, that's legal.' When asked if he supported legalizing marijuana, the president said he was not endorsing that. 'I wouldn't go that far, but what I think is that, at this point, Washington and Colorado, you've seen the voters speak on this issue.'"
You cannot reasonably defend one law as solely the purvue of the federal government and the other as "hey, we all have different expectations, Its cool"