After two years of nationwide protests over police treatment of blacks and other minorities, relations between citizens and police remain troubled, even as homicide rates are rising in most of the nation’s largest cities. But it is unclear whether the recent surge in urban violence means the nation’s decades-long decline in overall crime is ending. Justice Department interventions in some cities aim to overhaul departments where officers have exhibited a pattern of using excessive force. And in an era of cellphone and police body-camera videos recording interactions between police and minorities, officers disagree over whether to de-emphasize the use of force in potentially lethal confrontations. Some experts blame a falloff in preventive enforcement for the rise in crime, but others say it is not clear that a decreased enforcement trend is underway.

Police in Los Angeles respond to a murder-suicide shooting at UCLA in June that led to a campus lockdown. (Getty Images/Los Angeles Times/Genaro Molina)

Violent crime, including homicide, is increasing in many big cities, adding a new element to a national debate over police conduct toward minorities sparked by a series of deaths at police hands in recent years. Paradoxically, the geographically scattered increases come during a 25-year decline in violent crime nationwide, down 49 percent between 1990 and 2014, the most recent full year for which FBI statistics are available. 1

But homicides and other violence remain an ever-present danger, especially in some minority communities. During the first 10 months of 2015, the homicide rate had increased by an average of 16 percent a trend that continued this year, though it was driven by killings in a small number of cities, according to the nonpartisan Congressional Research Service. 2 In the first quarter of this year, data from the Major Cities Chiefs Association showed that homicides jumped sharply in some cities — by 60 percent in Newark, N.J., and 100 percent in others, including Long Beach, Calif. 3 Police and other experts cite several possible reasons: easy access to guns by young men with few job prospects, gang feuds, disputes over social media postings, an enforcement pullback by police in response to heightened public scrutiny — or some combination of these factors. 4