At the bank I was asked if my income would come from growing marijuana. The bank clerk said they ask this because it’s illegal on the federal level, even though legal in some states.
How can something be illegal on the federal level, yet legal on the state level?
Is there any special system where a state has the right to overrule federal law for some areas of law or some kinds of law?
Yes, Federal law overrides state law, but only if the Federal government has jurisdiction.
A way of thinking about this is that the states are sovereign, but have ceded some aspects of their sovereignty to the USA. In some cases, like the ability to enter treaties with foreign powers, the ceding is absolute - the states just can’t do that. In other cases, the states still have the power to make law but where the Constitution says the Federal government also has the power, Federal law wins if it conflicts.
The important thing is that the Constitution has to actually grant the relevant power to the Federal government; they can’t just make laws about anything.
Now, this gets complicated, but the most likely route for the Federal government to make laws about marijuana is the interstate commerce clause. The Federal government is allowed to regulate anything that impacts commerce that crosses state lines. You would think that commerce that happens entirely within one state would not trigger that power, but SCOTUS disagrees. If it can impact interstate commerce, say by affecting prices in other states, then that gives the Federal government an “in”.
With marijuana specifically, the Federal government has shown a general disinterest in enforcing laws that may or may not be constitutional; possibly because they don’t want to know for sure. However, if your bank operates across state lines (and they all do) then the Federal government is on much surer ground. Or, at least, your bank doesn’t want to be the test case.
