Nullification efforts are mounting in states across the country. Kansas recently made it a felony for federal agents to enforce federal gun laws on guns made in Kansas. A law here in Missouri recently passed with huge super-majorities, so it will come into effect regardless of whether Governor Nixon vetoes it. So my question is whether or not those laws are constitutional.
I'd like to make a distinction between those laws and the marijuana laws that have come into effect and are mentioned in the source as examples of nullification. Those laws merely legalize marijuana in the state, but do not prevent federal agents from enforcing the federal laws against it. As I understand it, this type of law was ruled constitutional in Prigg v Pennsylvania where it was said that the states cannot be compelled to use state law enforcement resources to enforce federal law. Rather, what I am talking about are laws that prevent even federal agents from enforcing the federal laws.