In a recent trip to a crime-plagued south Chicago high school, first lady Michelle Obama declared, in support of gun control, "If there is even one thing we can do, even one step we can take to save another child, then don't we have an obligation to try?" And President Barack Obama reacted in anger when Senate Republicans blocked the expansion of gun-purchase background checks.

But what if there is one step we can take that would save a lot more than one child, without upsetting even one gun-loving Republican? Shouldn't we take that step?

The White House has spent political capital fighting for gun restrictions even though research on the impact of gun control on crime is decidedly mixed, with results depending on the time periods, units of analysis, and statistical techniques analysts employ. (Violent crime actually fell over the past two decades even as guns proliferated.)

By focusing on gun-culture wars, our politicians overlook lessons from the most remarkable crime decline in modern history.

As Patrick Wolf and I show in our just published Public Administration Review article, "Cops, Teachers, and the Art of the Impossible: Explaining the Lack of Diffusion of Innovations that Make Impossible Jobs Possible," back in 1990, New York City had a record 2,245 homicides, threatening tourism and making the Big Apple a bad bet for business investment. In response, Mayor David Dinkins began to grow the New York Police Department and empower his innovative police commissioner, Raymond Kelly. Crime declined, but the best was yet to come.

After Rudy Giuliani unseated Dinkins, largely on the crime issue, he replaced Kelly with William Bratton, who in a frenetic two-year period remade the NYPD. Crime plummeted and has stayed low ever since. In 2012, New York had 418 homicides, the lowest in a half century. New York has more than three times Chicago's population, but last year the Big Apple had 17 percent fewer killings. How does NYPD do it?

First, ever since Bratton's tenure in the mid 1990s, the NYPD has focused on minor crimes like subway-turnstile jumping, sending the message that the cops control the streets. (As it turned out, many turnstile jumpers were wanted for serious crimes, so beat cops soon saw the wisdom of this approach.)

Even more important was CompStat, a computer program reporting crime in (almost) real time. CompStat enables police commissioners to push precinct commanders to target crime hot spots. Many cities, including Chicago, have CompStat; yet the program has underperformed outside of New York. Why?

A key explanation may be something as unsexy as public personnel policy.

In nearly all big city police departments, key officials are tenured civil servants beyond the reach of their chiefs. In contrast, NYPD commissioners have unusual power over subordinates. They can demote precinct commanders who fail to fight crime and choose their successors. In his first year as commissioner, Bratton replaced two thirds of precinct commanders with officers who shared his vision. Bratton forced complacent cops out of their comfort zones.

So why don't other police departments copy NYPD? That's probably because in most cities crime fighting has nothing to do with a police chief's career success. No matter how we crunched the numbers, Patrick Wolf and I found no relationship between a city's homicide rates and whether the police chief kept or lost his or her job. (We used homicide since other crime statistics are unreliable, but cops don't hide dead bodies.) It's common knowledge among cops that their chiefs get axed for scandals or for embarrassing mayors, not for high crime. Bratton himself was fired for the crime of becoming more popular than Giuliani, who saw his top cop as a political threat. What police chief wants to copy that?

If politicians really want to cut crime, they should create grant programs to encourage other cities to copy NYPD-style police accountability, just as the Obama administration's Race to the Top awards encouraged accountability in public education.

To paraphrase the first lady, reforming policing can save a lot more than one child, and we do have the obligation to try.

Robert Maranto is the 21st Century Chair in Leadership in the Department of Education Reform at the University of Arkansas.