The ONLY part of the Constitution that gave the Federal Government the power to regulate what ANY kind of drug was the 18th Amendment. It was limited to alcohol, and only to it's manufacture, sale, and transportation. There was nothing in it that ever gave the federal government the power to outlaw it's use:
Section 1. After one year from the ratification of this article the manufacture, sale, or transportation of intoxicating liquors within, the importation thereof into, or the exportation thereof from the United States and all territory subject to the jurisdiction thereof for beverage purposes is hereby prohibited.
Section 2. The Congress and the several states shall have concurrent power to enforce this article by appropriate legislation.
Section 3. This article shall be inoperative unless it shall have been ratified as an amendment to the Constitution by the legislatures of the several states, as provided in the Constitution, within seven years from the date of the submission hereof to the states by the Congress.
A constitutional amendment was required to do this with alcohol, and that amendment has since been repealed. What amendment gives the federal government the power to outlaw any other drug?...answer: There isn't one! Why can't the drug warriors see this as an opportunity instead of an obstacle? If it is true that the feds do not have the authority to ban drugs, then it also proves that it does not have the authority to establish federal departments of education, houseing, energy, transportation, health and human services and God knows what else? If you tollerate ONE of these then we will forever be inflicted with ALL of them.
The commerce clause of the Constitution grants congress the authority to regulate the drug trade. All other drug laws belong at the state level. Do you acknowledge that states have the authority to regulate drugs?