Constitutional Challenge: the war on drugs

My wife has been watching Breaking Bad and there is a scene where the main character Walter is talking to his brother about Cuban cigars and how arbitrary the line is between legal and illegal. For some reason this scene threw some fuel to my passion against the war on drugs.
I have spent a lot of time thinking about how a legal challenge to the drug war would go (because it's remotely possible that I will not be elected to congress). This may seem like an unlikely way to attack the war on drugs but people forget how much change Ralph Nader made as a citizen with a pack of like minded lawyers.
This is the approach I would take if I had a pack of like minded lawyers who would know if I am actually on to something here or not.
For the sake of the article I am only arguing for the legalization of marijuana because it clearly doesn't pose any public health risk outside of the fact that it is illegal/controlled by criminals. If precedence is set legalizing other substances can also be tested in court.

Amendment 21 - Amendment 18 Repealed. 
1. The eighteenth article of amendment to the Constitution of the United States is hereby repealed.
2. The transportation or importation into any State, Territory, or possession of the United States for delivery or use therein of intoxicating liquors, in violation of the laws thereof, is hereby prohibited.
3. The article shall be inoperative unless it shall have been ratified as an amendment to the Constitution by conventions in 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 while ago I had the idea that the 21st amendment should be applied to the war on drugs. But when I reread it I realized that it doesn't repeal prohibition as I remembered, it repealed the 18th amendment.

Amendment 18 - Liquor Abolished. 
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.
2. The Congress and the several States shall have concurrent power to enforce this article by appropriate legislation.
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.

Looking at the 18th amendment it is clearly Abolishing alcohol. I fail to see how I could make a convincing argument that it also should also apply to the prohibition of marijuana. But then I realized the argument shouldn't be made on the 21st amendment but on the existence of the 18th

Amendment 10 - Powers of the States and People.
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.

I was always told in Social Studies that the 21st amendment is the only amendment to overturn another, but it could be argued that the reason for the 18th amendment was passed to allow an exclusion to the limit of federal powers placed by the the 10th amendment. If prohibition was allowed by the exception of interstate commerce than why was it passed as an amendment?

If this ruling was passed in favor of my argument this would set drug policy back down to state level.  Or that is my non lawyer understanding of it.