Manhattan Institute fellow Heather Mac Donald has written extensively about crime and has a new op-ed revealing that, while Black Lives Matter has “convinced Democrats and progressives that there is an epidemic of racist white police officers killing young black men,” the “movement is based on fiction.”

Not just the fictional account of the 2014 police shooting of Michael Brown in Ferguson, Mo., but the utter misrepresentation of police shootings generally.

To judge from Black Lives Matter protesters and their media and political allies, you would think that killer cops pose the biggest threat to young black men today. But this perception, like almost everything else that many people think they know about fatal police shootings, is wrong.

The Washington Post has been gathering data on fatal police shootings over the past year and a half to correct acknowledged deficiencies in federal tallies. The emerging data should open many eyes.

For starters, fatal police shootings make up a much larger proportion of white and Hispanic homicide deaths than black homicide deaths. According to the Post database, in 2015 officers killed 662 whites and Hispanics, and 258 blacks. (The overwhelming majority of all those police-shooting victims were attacking the officer, often with a gun.) Using the 2014 homicide numbers as an approximation of 2015’s, those 662 white and Hispanic victims of police shootings would make up 12% of all white and Hispanic homicide deaths. That is three times the proportion of black deaths that result from police shootings.

The lower proportion of black deaths due to police shootings can be attributed to the lamentable black-on-black homicide rate. There were 6,095 black homicide deaths in 2014 — the most recent year for which such data are available — compared with 5,397 homicide deaths for whites and Hispanics combined. Almost all of those black homicide victims had black killers.

Police officers — of all races — are also disproportionately endangered by black assailants. Over the past decade, according to FBI data, 40% of cop killers have been black. Officers are killed by blacks at a rate 2.5 times higher than the rate at which blacks are killed by police.

Never mind these facts, though. Hillary Clinton and Bernie Sanders will be increasingly campaigning on the issue as they traverse the South during primary season.