Historically this was much more of a problem. The best example was the fugitive slave laws.
Many Northern states, simply said, “they weren’t going to enforce it period.”
And even if the state did enforce it, the local jurisdiction often would not do so. (As in Ohio may enforce the slave law but Cincinnati wouldn’t <-made up example)
But this is always not so problematic as seen with gay marriage.
You can be married in some states and not others. A gay marriage in Massachusetts is valid, but it’s not valid in Illinois and it’s not valid for the federal government.
Yeah I realize it’s not the same thing as there’s a criminal part to marijuana not present in gay marriage, but you see the point.
Another exmaple is cellphones and cars. This is not a federal / state thing but a state / city thing. Again two levels of government.
In some cities you can’t talk on a cellphone and drive. Fair enough, but you can talk on a cellphone and drive in the rest of the state.
Seems cut and dry, but not so, some courts have ruled, that since city boundries come and go a driver can’t reasonably be expected to know where he needs to turn off the cell phone. So the ticket’s not enforceable to certain people.
Gun laws are another issue, especially in California. This again is a state / city thing. A state will issue a valid gun license and a city will ban guns. Who trumps who? Well it depends on the state law and the way it’s enforced. We’ve seen in California, courts willing to say the state gun law rules over a local gun law.
In Illinois, Chicago has banned handguns and has successfully made it stick (so far). You can’t buy a handgun in the suburbs and bring it into Chicago. Because Illnois has said, Chicago’s home rule allows it. Other states with home rule have ruled otherwise.
This is confusing to people because the result is mishmash of laws. But when you look at it it’s actually common.
Another good example is our federal courts. We have many cases where a law has been passed and one federal appeals court will rule the law is consitutional and one federal court will rule it unconstitutional.
So what happens? Logic says, you go to the United States Supreme Court and they make the final ruling. And this has happened, but the SCOTUS often will decline to hear the case. The result is that both rulings are upheld.
This has happened more over the years as the federal appeals court based in San Francisco is more liberal than the rest of them. There in fact has been an effort to somehow require the SCOTUS to actually rule of conflicting opinions to straighten things out either way. So far that has failed.
In the case of the marijuana law most likely the federal agents will enforce it and the state will allow them. Why? Because that will bring it to the courts where they can (hopefully) get a “once and for all” final ruling.