D.C. Police Chief Peter Newsham. (Sarah L. Voisin/The Washington Post)
Opinion writer

There is no issue that has so dominated President Trump’s presidency and disfigured the GOP than obsessive, unhinged fear-mongering about illegal immigrants — which has now morphed into a broader mission against legal immigration. What was once a distressing fetish among a narrow group on the right has become — along with protectionism — a rallying call for a party disinclined to pay attention to facts (and Labor Economics 101) and determined to humor the aggrieved white non-college educated working class that has been fed a steady anti-immigrant diet by Fox News and other right-wing media.

Anti-immigrant voices’ smokescreen that they were only opposed to illegal immigration has been shredded. They now revel in their calls for immigration exclusionism. If allowed to persist, it will distort and damage our economy and impede entrepreneurship. It has already encouraged a wholly-misguided approach to crime fighting.

Attorney General Jeff Sessions and Trump have concocted a theory that we are awash in crime because of illegal immigrants, especially those living in “sanctuary cities.” That is patently false, and Sessions’ efforts to punish cities that refuse to do the feds bidding in detaining and helping to deport illegal immigrant have been swatted down in court. However, the barrage of litigation over sanctuary cities and obsession with the issue has led us to ignore both the successes and failures in crime fighting — and the causes of each.

The Wall Street Journal reports this week (in step with reams of other reports and studies over the last few years) that crime is affected by local conditions, not immigration policy. The report examined “the locations of thousands of homicides in four cities: Chicago and Baltimore, where violence has risen to or near 1990s levels in the past two years; and Los Angeles and Washington, D.C., where meaningful declines in violence have been sustained since the 1990s.” (All four have been criticized by anti-immigrant groups for failing to cooperate sufficiently with feds — when, for example, there is no warrant to detain suspected illegal immigrants.)

According to the data, “the neighborhoods where killings have soared in Chicago and Baltimore share worsening poverty, high numbers of vacant houses, and a lighter street presence by police following officers’ high-profile killings of young black men.” By contrast, “In Washington and Los Angeles, gang interventions and community policing, which seeks closer contact with residents to gain trust and even information in to address crime, have helped produce long-term reductions in murders. Gentrification in the nation’s capital also has played an important role in keeping violence down.” The deference between success and failure often boils down to how police interact with a handful of neighborhoods. (“George Mason University criminologist David Weisburd said his research has shown that about 1% of city streets produce 25% of a city’s crime, and 5% of the streets produce half the crime. He calls it the ‘law of crime concentration.'”)

So when the Justice Department threatens to yank funding from local law enforcement or demands that authorities undercut the relationships they’ve built up over years to earn the trust of those affected by crime, he is quite simply making cities more dangerous.

In Baltimore, illegal immigrants have nothing to do with the crime epidemic. (“Since the unrest [after the Freddie Gray killing], arrest numbers in the city are down. The police force is also at reduced strength because of retirements and resignations that have left it with 2,500 sworn officers, or about 500 fewer than in 2012. And eight officers were indicted this year on federal charges that included robbing citizens; five have pleaded guilty. ‘You look at Baltimore’s crime numbers, that’s criminals taking advantage of weakness,’ Mr. Barksdale said. He added: “I am against mass arrests, but you still need arrests.”) The residents are practically begging for a more involved, robust police presence. (“Jacqueline Caldwell, a local resident who leads a nonprofit umbrella group that includes several west-side community associations, said the police have become nonexistent over the past two years. ‘I don’t think it takes a rocket scientist to figure out we need more police on the street, more community involvement with the police,’ Ms. Caldwell said.”)

By contrast, in Los Angeles — where the number of illegal immigrants dwarf all other major metropolitan cities but one — crime has dropped precipitously. “According to the FBI’s Uniform Crime Reporting Statistics, the LAPD reported the violent crime rate per 100,000 people declined from 820.6 in 2005 — the year [Mayor Antonio] Villaraigosa took office — to 426 in 2013, the year he left office. That represents a 48 percent reduction in the violent crime rate, homicide, rape, robbery and assaults.” Part of the credit goes to hiring more police, but criminologists also attribute the decline to the “focus on community policing and crime prevention and intervention.” The current police chief cites the positive impact from “diverting at-risk youth from gangs; recruiting gang members to prevent conflicts between rival gangs from flaring up; and handing out grocery store gift cards in exchange for guns.”

So when Los Angeles mayors and police chiefs tell the Justice Department that making police into immigration agents will impair their community policing success and divert valuable resources, maybe we should listen to them. Conservatives used to understand that in federalism we have the “laboratories of democracy,” namely the opportunities to find through experimentation what works and what doesn’t. Rather than riding roughshod of localities, Sessions should highlight the successes of local police departments, urge others to follow suit and increase funding — rather than threaten to yank it for spurious reasons — for those localities that need it the most. Alas, his ideological fixation with demonizing illegal immigrants seems to preclude such a fact-based approach.