Recent FBI statistics show that there is at least a "causal relationship" between reduced policing in cities that suffered from anti-police violence and violent crime.

The most glaring example is Chicago, where police have come under withering attack for several high-profile killings of unarmed civilians.  The murder rate went up an astronomical 86% from 2014 to 2016.  Other cities, including Dallas, Baltimore, Milwaukee, St. Louis, and Charlotte, also experienced spiking numbers of murders.

The common factors in all those cities were protests and riots against perceived police brutality.

Daily Caller:

As McDonald [sic] sees it, agitation by groups such as Black Lives Matter, encouraged by slanted media coverage, has led to a retrenchment among big-city police forces. Street cops are so worried about being vilified by city leaders and the press that they are avoiding contact with the criminal element, she says.

"Cops are backing off of proactive policing in high-crime minority neighborhoods, and criminals are becoming emboldened," MacDonald [sic] wrote in a Sept. 25 piece for City Journal. "Having been told incessantly by politicians, the media, and Black Lives Matter activists that they are bigoted for getting out of their cars and questioning someone loitering on a known drug corner at 2 AM, many officers are instead just driving by."

Critics have said MacDonald's [sic] theory is not supported by statistical evidence, noting that big spikes in violence occurred in just a handful of cities. If the Ferguson Effect were a real phenomenon, they argue, it would have manifested itself across the country.

"It's really a local problem, not a broad trend," Ames Grawert, an attorney with the Brennan Center for Justice, told The Intercept in 2016. "There is no evidence that crime has gone up overall."

Another year's worth of FBI data, however, adds weight to MacDonald's argument. Killings have spiked in several cities that experienced rioting or significant protest against the police.

Dallas, for example, recorded 171 murders in 2016 – 47 percent more than in 2014. The story was the same in Charlotte and Milwaukee, whose 2016 homicide totals were 43 and 57 percent higher than in 2014, respectively.

Nowhere is the correlation between reduced police activity – what MacDonald [sic] calls "de-policing" – and a higher number of murders stronger than it is Chicago.

Earlier this year, the University of Chicago issued a report on the data behind the city's horrifying rise in gun violence in 2016. After concluding the wave of murders couldn't be attributed to warm weather or a decrease in educational or social welfare spending, the report suggested a precipitous drop in police stops might be a causal factor.

It isn't just officers being worried about getting into trouble for stopping people.  There is real fear on the streets.  Targeted assassinations of police officers are rising as black activists use white-hot rhetoric to describe police as "terrorists" or "targeting" black males.

Every time an officer gets out of his patrol car in a high-crime area, he has to be wondering if there is a shooter out there.  This is the reality that police officers face and is certainly a part of the "Ferguson Effect."

Politicians in big cities have shown they do not have officers' backs.  This contributes to the feeling that cops are alone and is a huge disincentive for them to enforce the law.

The Ferguson Effect is real.  How many more cops have to die to convince anti-police activists of that fact?