True. No Federal Drug War.
You could, however, have 50 Drug Wars going on at the State level.
Way too many libertarians don't realize that the Constitution is not a libertarian document. It's a document that established a federal government with limited powers.
State governments had almost no restrictions put onto them by the Constitution. Initially, even the Bill of Rights did not apply to the states, which could and did interfere with freedom of speech and press, for instance.
You could indeed. But we know of at least two that wouldn't be waging a War On Marijuana - and several more that wouldn't be waging a War On Medicinal Marijuana.