The Drug War would indeed be a failure if its real function was to reduce drug consumption or drug-related violence. But the success or failure of state policies is rightly judged by the extent to which they promote the interests served by the state. The Drug War is a failure only if the state exists to serve you.
Unintended consequences or deliberate strategy? Either why some have a vested interest in continuing the war on drugs.
See on www.counterpunch.org