Andrew Bailey is up to bat. The pertinent points are:

The precedent is clear, the federal government has no authority whatsoever to compel a state to enforce a federal law. So, what’s the difference here? Sadly, all too many federal judges stubbornly believe the Second Amendment is a second-class right. In the case of the recent ruling against SAPA, the Eighth Circuit simply invoked the Constitution’s supremacy clause, and gave the back of its judicial hand to Missouri and every other state that might question the constitutionality of a federal law — at least a federal gun law.