The last time America had a gun-control debate was the early 1990s, and it was followed by the great two-decade-long decline in American crime. The irony is that gun control had very little to do with that decline.

William Bratton did. Serving as New York City's top cop for 27 months from 1994 to 1996, he helped turn around a violent, crime-ridden city with policies that later were adopted nationwide and across the globe. The 65-year-old now runs a consulting business and a tech firm that focus on law enforcement, and in a recent chat he puts the gun debate in the context of policies that really have made America safer.

As announced Wednesday, President Obama wants more federal and state information-sharing, more data collection and better training for local law enforcement. But the heart of his proposals, and the most controversial, are his requests that Congress reinstate the ban on "assault weapons" that lapsed in 2004, outlaw ammunition clips holding 10 or more rounds, and extend mandatory background checks to almost all gun sales.