I really need to write this up in a post of it's own, but the drug war is motivated by "rent-seekers" (people that seek power and kickback via government influence) and "do-gooders" (people that seek to gain social capital by making the appearance of caring...usually on someone elses' dime).
The combination of "rent-seekers" and "do-gooders" can be looked at in an analogy from Prohibition; the "Bootleggers and Baptists" problem; the bootleggers wanted to keep booze illegal because that meant higher profits, while the Baptists wanted to fight "demon rum". In the meantime, the Constitution was trampled and spit on.