This should make it to the U. S. Supreme Court. No matter how it is decided, the outcome should lead to interesting results. Either Federal law is supreme and must be followed and enforced or state/local governments can chose for themselves whether to recognize Federal laws. I see plenty of angst all around.
Federal Law is Supreme.
Supremacy Clause
The Supremacy Clause of the United States Constitution establishes that the Constitution, federal laws made pursuant to it, and treaties made under its authority, constitute the supreme law of the land. It provides that state courts are bound by the supreme law; in case of conflict between federal and state law, the federal law must be applied.However, the courts have ruled that State and local LE cannot be compelled to "Enforce" Federal Law.
Marijuana is a prime example. Pot is illegal according to Federal Law. States cannot "legalize" marijuana as that would be a violation of the Supremacy Clause of the Constitution. What they can do and are doing is "decriminalizing" pot, meaning their is no State Statute prohibiting it's use or possession and will not use/spend State and local resources to enforce Federal law . With that, States that have decriminalized pot cannot prevent Federal authorities form enforcing Federal Laws withing their borders.