Paul Butler, a former federal prosecutor, is the Albert Brick Professor in Law at Georgetown University. He is the author of “Chokehold: Policing Black Men.”

If anybody but a cop had written this book, few would believe the stories it contains — at least few white people. “The Black and the Blue” has enough accounts of police atrocities to launch a thousand Black Lives Matter marches.

There are the familiar cases of Michael Brown in Ferguson and Laquan McDonald in Chicago, young black men gunned down and then treated, in death, more like criminals than the white cops who killed them. Matthew Horace’s analysis is well researched and cogently presented, even if his ideas are not particularly new or creative. His thesis is that the problems of policing minority communities are systemic: Cops do not have adequate training for predictable situations they encounter, such as dealing with addicts and the mentally ill; they are given the impossible task of addressing problems that stem from structural race and class inequalities; and the sociology of policing encourages a warrior “us against them” mentality.

Other works, from the Justice Department’s Ferguson report to President Barack Obama’s Task Force on 21st Century Policing to the edited volume “Policing the Black Man” have made essentially the same points. What’s different about “The Black and the Blue” is that it’s a cop on the force for 28 years making the case for change — an African American cop.

Horace uses his insider status, and no doubt interrogation skills he learned on the job, to get a number of police officers to tell tales out of school, including out of the police academy. One of them, Tony April, was a rookie Alaska state trooper whom white officers tried to get kicked off the force, simply because he was black. April went on to become Trooper of the Year.

It’s these new stories, heretofore unknown except by the cop perpetrators and their victims, that are most horrifying because Horace presents them as everyday work. Brian Mallory, a New York police detective, was questioned by a Latino kid whom he ordered off a street corner. As Mallory tells it himself, “I get out of the car with my night stick and club him until he drops.” This happened in 1983, and Mallory seems almost nostalgic when he observes that an officer would not get away with this today because of cellphone videos, social media and more vigilant internal-affairs departments.

“The Black and the Blue,” co-written by Ron Harris, a Howard University journalism professor, does an exemplary job of indicting the system, but sometimes what people want is the indictment of an individual officer. After more than 200 pages, the reader is not told whether Horace thinks officer Darren Wilson did anything wrong when he shot Brown on the street in Ferguson. Horace states that Brown was “confrontional” and “high,” but also that he’s never stopped anyone for “manner of walking in roadway,” the original reason Brown was stopped. Horace’s critique of Jason Van Dyke, the Chicago police officer who shot Mcdonald 16 times, is less muted.

Still, it’s not police conduct that inspires the level of emotion that Horace calls his “personal reckoning.” Rather, it’s the tragic execution-style shooting of four teenagers in a suburb of Newark as part of a gang initaition. Horace trots out the tired canard that “if black lives matter, all of them must matter,” not only the ones who are victims of police violence. This is the same false dichotomy espoused by the likes of Rudy Giuliani and President Trump. No one in the movement for black lives excuses any taking of life. Indeed the movement’s platform proclaims the need for a holistic response to the broad spectrum of violence that black people face.

Still, between the black and the blue, Horace seems mainly to side with the black, because like most African American men, he has had his own set of experiences with the cops, including having a police dog sicced on him and, while working undercover, having a white cop put a gun to his head.

When I was a federal prosecutor, I quickly learned that I had to be discerning in how I used black investigators. Posting black undercover officers on lookouts, where they were supposed to observe a suspect’s house, or asking them to do “garage dumps” — a time-honored law enforcement technique of going through a suspect’s trash can — almost always invited a visit from the local police. Fortunately none of my investigators got hurt. New York state experienced so many instances of black undercover officers being shot on duty that it funded a special task force to address the issue.

In the introduction to “The Black and the Blue,” Horace identifies with two sets of people. The first are police officers killed in the line of duty or responsible for heroic acts, such as rescuing a child from a car teetering over the edge of a hill. Just reading these tales of valor reminded me that I could never be a police officer; I am not that brave, and I am grateful that some people are.

The second group Horace holds up are black males such as Harvard professor Henry Louis Gates Jr. and 12-year-old Tamir Rice, subject to police abuse simply because of their race and gender. Horace allows that there were times he almost made that same mistake, but he apparently always checked himself before any real damage was done. Throughout the book African American officers are presented as people at the tragic center of a swirling vortex.

In reality, the intersection of black and blue is more nuanced and more fraught.

I once pitched an op-ed to a magazine editor about my experience of being racially profiled by cops while walking in my own neighborhood in Washington. The editor resisted, saying that those kinds of stories were a genre (and this was back in the 1990s!) and that I’d have to have something new to say. My rejoinder was that the four cops who profiled me were black like me. She published the story.

In hip-hop culture, African American officers are frequently presented as worse than white ones. As the lyrics of the seminal group NWA put it: “Don’t let it be a black and a white one/ ’Cause they’ll slam ya down to the street top/ Black police showing out for the white cop.” Some new social science research suggests that African American officers are at least as likely as white officers to shoot an unarmed black man. James Forman Jr.’s Pulitizer Prize-winning book, “Locking Up Our Own,” contains the best history of black cops, and the lesson he draws is that African Americans should become police officers because it’s a decently paying job with good benefits. But, in Forman’s telling, we should not expect African American officers to treat black people any differently than white officers do. There’s something about the blue that colors over the black.

“The Black and the Blue” is an important contribution to a growing body of work about minority police officers. Horace’s authority as an experienced officer, as well as his obvious integrity and courage, provides the book with a gravitas that might convince some readers apt to turn a blind eye to the activists and scholars who are the primary critics of racialized policing. All these voices are needed to hasten the day when neither the police officer’s spouse, nor the African American parent, has to issue the warning “Be safe out there.”

The Black and the Blue

A Cop Reveals the Crimes, Racism, and Injustice in America's Law Enforcement

By Matthew Horace
and Ron Harris
Hachette. 236 pp. $27