There have been no successful tools against the war on drugs, only a tremendous violation of our constitutional rights with a few show trials to keep us all believing in the childish fantasy.
If you're going to say something is successful, be clear about it. Yes, it has been successful at locking up more people than any country in the world. Yes, it has been successful at seizing tons of property. No it hasn't been successful at putting any sort of dent into organized crime, which is fueled by the gigantic black market of drugs.