Legalize more drugs. Figure out what the black market needs to make a profit and tax the legal and safer comparable drugs until they are almost that expensive. This undercutting will put gangs out of business which will reduce costs to police forces and court systems.
Fewer people going to prison because of possession of drugs or using drugs means less money going from our states to the courts and to the for-profit prison system.
Increasing revenue, reducing gang violence, reducing expenditures- why aren’t we on this already? Oh, right. Because we’d rather say we are tough on crime than actually reduce crime.