One of this morning’s big news stories is the fatal shooting of 18-year-old Antonio Martin by a policeman in Berkeley, Missouri–a place that, the Associated Press tells us helpfully, is “just a few miles from Ferguson.” The Antonio Martin shooting is currently the top story on Google News, and it is being headlined on pretty much every newspaper’s website.

But why? What makes this a major news story? The Michael Brown and Eric Garner stories that preceded it, obviously. But what made them worldwide news? Or, to go back in time, what made the Trayvon Martin case a cause célèbre, commented on by the President of the United States and followed breathlessly by millions?

The Antonio Martin case won’t be as big a story as Brown’s and Garner’s deaths. Rather than being your typical “unarmed” 300-pounder, Martin apparently pulled a 9 mm. pistol on the policeman who responded by shooting him. But every shooting of a civilian by a police officer is now deemed an important news story–with the critical qualification that the civilian, but not the officer, be black.

Are these shootings worldwide news because of an epidemic of racist murders being carried out by American policemen? That is what Eric Holder, Bill DeBlasio and Al Sharpton would have us believe. But it obviously isn’t true. Heather Mac Donald writes:

Police killings of blacks are an extremely rare feature of black life and are a minute fraction of black homicide deaths. The police could end all killings of civilians tomorrow and it would have no effect on the black homicide risk, which comes overwhelmingly from other blacks. In 2013, there were 6,261 black homicide victims in the U.S.—almost all killed by black civilians—resulting in a death risk in inner cities that is ten times higher for blacks than for whites. None of those killings triggered mass protests; they are deemed normal and beneath notice. The police, by contrast, according to published reports, kill roughly 200 blacks a year, most of them armed and dangerous, out of about 40 million police-civilian contacts a year. Blacks are in fact killed by police at a lower rate than their threat to officers would predict. In 2013, blacks made up 42 percent of all cop killers whose race was known, even though blacks are only 13 percent of the nation’s population. The percentage of black suspects killed by the police nationally is 29 percent lower than the percentage of blacks mortally threatening them.

These stories about the killings of African-American men by police officers (or by a “neighborhood watch captain,” in Trayvon Martin’s case) are all what my long-time radio and podcast partner Brian Ward calls “stories of choice.” They are plucked from a nearly endless supply of sad events that occur daily in a nation of 315 million, and are promoted because they further a political narrative. An unholy alliance of activists and newspaper reporters and editors tries to distort our perception of reality by giving undue emphasis to them. Then, of course, reality begins to catch up with perception, and we have riots, murders of police officers, and so on. But understand that the decision to promote these stories, in preference to others that are equally or more newsworthy, is a choice that is consciously made by people with a political agenda.