"Nullify" is a conveniently safe and vague choice of words here. I say this is all smoke and no fire. Pay no attention to the man behind that curtain.
Is "nullifying a law" even a term with any legal meaning? I've heard of repealing a law or declaring a law unconstitutional or even overriding a law, but not nullifying one. No, of course a state legislature in a federal republic does not have the power to repeal a federal law, or to pass legislation declaring their state and its residents explicitly exempt from a federal law. But local and state-employed law enforcement officers do not generally charge citizens with violations of federal law, because it's tediously bureaucratic to do so. Most things they charge people with that are illegal under federal law are also illegal under state law, so they just charge people with violating the state law, and issue them a summons to appear in a state-administered local court, which is far easier to arrange. Examples like marijuana possession -- illegal under federal law, legal under state law,
and commonly encountered in the general public by local and state patrolmen -- are relatively uncommon, and I imagine would tempt most state-employed cops in legalized states to turn a blind eye.
Only LEOs that are employed by forces under the direct control of the federal government regularly hand down federal charges to people. If you're in a legalized state, it would be good to know which LEOs fall under this jurisdiction, and avoid having pot on you if you're anywhere they patrol. I know customs and immigration officers, national park rangers, postal police, and US Marshals are some examples. This is not hard to do, as all of these forces have relatively easy jurisdictions to steer clear of. The DEA is the only federally-employed force I'd truly be scared of if I were an ordinary citizen heavy into the marijuana trade in a legalized state. They're disturbingly untouchable.
Yes, in theory there is nothing stopping the federal government from mobilizing a large number of LEOs under its direct command to states that have passed state laws legalizing marijuana, kicking in tokers' doors far and wide and putting the fear of federal law into the hearts of the citizenry. But I have a hard time seeing this really happening, unless the local legal status of marijuana causes the federal government some sort of big or costly collateral problem it can't afford to ignore, such as large numbers of drug tourists from far off places causing friction with the locals. But even that is a bit far fetched.
So does federal law actually "trump" local law? Not really, because it doesn't work like that -- state/local law and federal law do not have a nested or hierarchical relationship. The actual enforcers of federal law are much fewer and father between in most US communities.
What I do foresee is the DEA picking on (or picking off, as the case may be
) a few hapless token tokers as a publicity stunt every now and then, to look like they're doing something about it. Oh, and every now and then an empty-threat press release like this.
Now, what would be a real turning point in US legal history, and which I could possibly see happening if there's enough pressure from powerful groups that benefit from marijuana's illegality, is a US Supreme Court order that the states with legalized marijuana re-illegalize it, setting a precedent that anything banned by federal law as contraband must be banned under state law by every state. This would be a major overturning of the states' rights laws passed in the 1860s, and would call into question just how federalist the US really is.
Worse yet, but relatively less likely, I could see a national referendum for the federal legalization of marijuana winning a majority of votes, but the federal government (or even just the DEA, invoking some strange power of theirs) refusing to honor the referendum, citing some concern over public safety or ordinary citizens not being good judges of what's good for them or for society. That would set an even worse precedent, and would be all the proof we'd need that we're not a real democracy.
