More dogged enforcement, herding more violent people into prison, and holding them longer.
One of the effects of taking dope users/dealers off the street is that you end up taking a lot of violent people off the street. Four or five years ago, I pored over the data. Thirty-some percent of federal prisoners are in for drug offenses. Most of our prison population is in state pens, and in my state, only 19% of prisoners are in for drug offenses. This contradicts the popular misinformation that our prisons are made up mostly of drug offenders.