The United States is a nation governed by law at the federal,
state and local levels. Sometimes these laws differ with each
other. That's where the great principle of federalism comes in.
Federalism permits state laws to be in conflict with each other,
and even with the federal government. But that's OK. The
sometimes messy business of federalism permits different locales
to try different solutions to vexing problems, allowing the
states to act as the "test tubes of democracy." We see
federalism in action most vividly today surrounding the
controversy over medical marijuana. Ten states have either
legalized cannabis for medicinal use or permit a medical purpose
defense against prosecution. Their actions do not force other
states to go along. But federalism also means that the federal
government can't be compelled to accede to the state's laws,
either, and indeed, when federal and state laws conflict - as
currently it does in states that have legalized medical
marijuana - both federal and state laws may operat