[rm_-rf_slash]

That doesn't really change much. The constitution is the law of the land, so if it says nothing about drug use while a federal law bans a set of drugs from sale and use, then that's the law, unless it contradicts the constitution, and in that case, it's up to the Supreme Court to decide.

[antognini]

Well, not quite. The Constitution is set up to delimit the powers of the federal government. As the 10th amendment states, "The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people." So if a particular law exceeds the power granted to Congress by the Constitution, it is unconstitutional. It's not that the Constitution prohibits Congress from doing certain things and everything else is by default allowed. The Constitution allows Congress to do certain things and everything else is by default not allowed.