“Could you name an African-American organization that has committed violence against police officers?” Representative Karen Bass asked Attorney General Jeff Sessions at Tuesday’s hearing. “Can you name one today that has targeted police officers in a violent manner?” It’s no surprise that he could not. Mr. Sessions, who confessed that he had not read the report, said he would need to “confirm” and would reply in writing at a later time. The F.B.I. itself admits in the report, that, even by its own definition, “B.I.E. violence has been rare over the past 20 years.”

The Black Identity Extremist designation erroneously presumes a broad and disparate group of organizations with concerns about the criminal justice system represent a movement with a unifying ideology. This reflects ignorance — or denial — of the reality on the ground: There are dozens if not hundreds of groups with primarily black members that take issue with racial injustice but have distinct areas of focus, mandates, missions and memberships, and which are just as likely to conflict with one another as they are to overlap.

Beyond that, the F.B.I.’s suggestion that people with “extreme black identities” may attack law enforcement officers has practical — and potentially deadly — consequences for those who are swept up under the newly created label. Although it’s unclear what actions the F.B.I. will take as a result of the report, the conclusions pave the way for it to gather data on, monitor and deploy informants to keep tabs on individuals and groups it believes to be B.I.E.s. This could chill and criminalize a wide array of nonviolent activism in ways that have terrifying echoes its infamous Cointelpro program, which investigated and intimidated black civil rights groups and leaders, including Marcus Garvey and the Rev. Dr. Martin Luther King Jr. Under this program, F.B.I. agents concocted a false internal narrative connecting Dr. King to foreign enemies, allowing agents to justify threatening to publicize his private life and encouraging him to commit suicide. This is a reminder that while the “Black Identity Extremist” designation is new, the strategy of using a vague definition to justify broad law enforcement action is not. The report’s labored efforts to link what it calls the “violent anti-white rhetoric” of today’s black organizations to “B.I.E. violence” that “peaked in the 1960s and 1970s” suggests a plan to use similar tactics to the “monitor, disrupt and divide” approach that it used against civil rights activists.

The F.B.I.’s branding of individuals and groups troubled by racial injustice and police misconduct as dangerous “Black Identity Extremists” echoes and validates the way racist fringe groups on the right, like neo-Nazis or the K.K.K., see these activists. By encouraging the public to view groups like Black Lives Matter (which has offered a robust critique of systemic police violence against African-Americans and has organized peaceful direct actions but has no links to terrorism or violence) as a threat, the designation indirectly emboldens private violence against black activists. To make matters worse, the F.B.I. memo comes at a time of mounting white supremacy and white nationalism, and as the Trump administration has announced plans to cut Countering Violent Extremism funds to fight against white supremacists and neo-Nazis despite their having actual historical links to violence.

Finally, the F.B.I. designation compounds the vulnerability of black Muslims, who make up the largest segment — at least 25 percent — of the Muslim population in the United States. Muslim communities are already the targets of counter-radicalization policing. Neighborhoods, campuses and institutions where black Muslims organize around racial justice and against police brutality could now be doubly scrutinized with double the threats to civil liberties, particularly as the Trump administration seeks to intensify counter-radicalization measures.