Or does the federal law supersede the state law?
Yes, Fed. law does supersede State law.
There are currently 18 States plus DC in which med. mj is legal by State law but still illegal per Fed. law.
See list here:
IMO, something being made State legal but still against Fed. law does nothing but set the grounds for 'bad mojo waiting to happen'....and if I don't miss my guess, there will be some bad things happen(Feds. busting State legal med. mj. institutes, etc.) out of the whole med. mj State versus Fed. law issue.
As things stand now, it's just bound to happen.
Guess it would make to much sense to either completely legalize it per State and Fed. law same as alcohol or make it totally illegal before the 'bad mojo' hits.
But that's our 'gubment' for ya.