Yet since 2010, the two largest police agencies, the City of Miami and Miami-Dade County police, have handled 71,628 mental-health-related calls—and have made only 138 arrests. Miami-Dade taxpayers were on the hook for millions of dollars from wrongful-death lawsuits; today, fatal shootings are down almost 90 percent. More than 20 percent of those in county jails had serious mental illnesses, costing many millions to keep them there. Recently, the decline in arrests and incarcerations enabled the county to close a jail and save taxpayers $12 million a year.

What changed? A comprehensive program to transform structurally the way the community responded to people with mental illnesses (which Miami-Dade County Judge Steve Leifman, one of the authors of this piece, initiated). A key component was the CIT training of over 5,400 police officers in Miami-Dade, representing all 36 police departments, using a 40-hour program crafted initially in Memphis, Tennessee, in the late 1980s. To be sure, it was not easy. First, many police officers believe they know what they are doing and don’t think they need additional training. Second, it was a battle to convince police chiefs to take their cops off the beat for a week to take the course.