What's the difference between ignoring and not enforcing, I mean hell Obama "prioritized" enforcement of laws, then say we will no longer prosecute certain laws, why can't states do the same?
They can and do. If you only have so much to pay LEO to enforce the laws you are gonna give some laws more attention than others, which happens every where all the time (certain traffic laws, sodomites, etc.). What's the fed gonna do, force them to enforce the law without the funds to pay for enforcement?
That question is intended to be rhetorical but I think fedgov might have a different opinion of what the obvious answer is.