You’ve studied criminal law and policing for two decades. Is crime out of control in American cities?

Crime rates in the United States are at historic lows. Homicide and violent crime, in particular, are less frequent than they were at any time in the 1970s, 1980s, 1990s, or the early 2000s. That’s true almost everyplace in the country, including in most major cities. The homicide rate in Los Angeles is about a quarter what it was in 1990; in New York City it’s about an eighth. There are cities like Philadelphia where homicide rates have recently been ticking up, but those are still much safer places than they were twenty-five years ago. Chicago is an outlier; homicide rates there are almost, but not quite, as high as they were in 1990, and it’s not clear why.

President Trump has raised concerns that illegal immigrants are responsible for a considerable amount of crime in the U.S. Does the data support that concern?

That’s demagoguery. There’s zero evidence that undocumented migrants commit a disproportionate share of crime in the United States, and quite a bit of evidence the other way. The best proof, maybe, is the relatively low rates of violent crime and property offenses in border cities like San Diego, Laredo, El Paso, and Brownsville. Those are places with very high concentrations of noncitizens, including undocumented migrants, and they are strikingly safe. San Diego, El Paso, and Brownsville have lower homicide rates than Des Moines. The rate in Laredo is only slightly higher.