Actually feds have raided states with legalized MJ
However the question you need to ask is who has more rights or whose rights take precedence over the other: the individual, the state gov't, or the federal gov't
And it goes down to the word "discretion" the gov't retains absolute discretion for the laws they can choose to enforce or not enforce. Don't blame me blame the gov't.
This is why if the gov't sets its eyes on you, they will find hundreds if not thousands of ways to fark you over with their laws if they want. Sodomy is against the law, in many states you don't see them arresting porn stars and knocking down doors anymore right?
However if you tend to go with someone who is younger than the say certain age, all of a sudden that "never really enforced" law is now used against you, even tho there are other laws that already cover against that. So you are hit with 2 charges instead of one, when one of them is rarely to never ever enforced.
Same thing in Fugerson, the don't walk on the street law, never really enforced but see a "blackie" ( cop mentality ) all of a sudden that law is now enforceable. In Arizona, maybe see a "spanish brownie", law become fully active.
Just like providing material support to terrorist is AGAINST the Law, yet the USA is the biggest ARMS DEALER in the world, who funded Bin Laden, Saddam Hussien had loads of US bills, who fund our new ISIS allies, yup the US Gov't. We are the biggest state sponsor of terrorism. We want a nuke free world, well guess who supplied nukes to many of the countries that didn't have nukes in the first place.
Is that fair or a miscarriage/unfair/inappropriate/unconstitutional use of justice/punishment/application of law: That's something you can ponder on
There is a old saying man in itself are all capable of great evils, however when men becomes a group by formation of a "gov't/or authoritative body" they now can institutionalized/justify those evils
Which is why the biggest law breakers are the gov't itself, or ones who make their laws