Last weekend, UAW Local 2865 became the first local to call for the expulsion of a police union from the AFL-CIO, insisting in a resolution that the federation kick out the International Union of Police Associations (IUPA). It was a laudable move that evinced a commitment to social movement unionism — other locals should follow suit.

The UAW local, which is comprised of 13,000 teaching assistants and other student workers on University of California campuses, specifically decried cop unions’ lobbying against oversight, support for politicians opposed to police accountability, and dogged defense of officers accused of abuse.

“Historically and contemporarily,” the resolution reads, “police unions serve the interests of police forces as an arm of the state, and not the interests of police as laborers.”

So what business do academic workers have passing resolutions against police officers? The better question, amid an upsurge against lethal policing, is how unions should relate to popular movements that it hasn’t directly birthed.

Social movement unionism recognizes that labor isn’t a sectional interest, and it shouldn’t behave like one. It should instead place itself at the center of struggles that improve the lives of workers and take on social injustice. The proper constituency of a union isn’t simply its membership, but the entire working class.

As their record since the emergence of the Black Lives Matter movement demonstrates, police unions aren’t institutionally equipped to be anything other than anathema to this cause.

After a grand jury exonerated the Staten Island police officer who choked Eric Garner to death, Patrick Lynch, the president of New York City’s largest police union, lauded the jury decision and pointed the finger at Garner himself. “Mr. Garner made a choice that day to resist arrest,” Lynch opined in December. When two police officers were tragically slain a couple weeks later, Lynch accused Mayor Bill de Blasio of fostering anti-cop enmity and thus having “blood on his hands.”

The rank-and-file clearly approved of such bilious statements, turning their backs on de Blasio at the police officers’ funerals and then reelecting Lynch last month. (Lynch now characterizes his relationship with de Blasio as “respectful,” but such amicability only came after the mayor essentially spurned the Black Lives Matter movement.)

Police unions outside of New York City have also behaved deplorably over the past year. The police union representing Ferguson cops raised money online for Darren Wilson, Michael Brown’s killer. Baltimore’s did the same for the officers charged in connection with Freddie Gray’s death. And the Cleveland Police Patrolmen’s Union raffled off a Glock as a fundraiser for the cop accused of killing eighteen-year-old Brandon Jones.

Earlier this month, Baltimore’s police union released a report pillorying the mayor and police chief for their handling of the uprising in April. One local official aptly described the report’s tenor and conclusions: “they [were] upset because they wanted to go out there and bust heads and take charge.”

It’s precisely this reach-for-the-baton worldview that spurred the UC academic workers to seek the removal of the IUPA, the only union in the AFL-CIO that exclusively represents law-enforcement personnel. (AFSCME also has some members who work in law enforcement.)

When confronted with information of police unions’ misdeeds, many progressives accuse the bearer of anti-union animus. But if the Black Lives Matter movement has taught us anything, it’s that cops are different from other public-sector employees.

Social workers and teachers don’t fire bullets into the hearts and heads of unarmed people, or impose brute order when social unrest proves too acute for less coercive pacification. The word “union” shouldn’t be treated as an acid bath that magically disappears this social function. As Kristian Williams reminds us in his indispensable Our Enemies in Blue, “Police organize as police, not workers.”

Hoping for reform-minded police unions is also delusional. The GI movement encouraged rebellion within the ranks to terminate the Vietnam War; police unions, by contrast, have repeatedly fought to retain and expand the state’s coercive apparatus.

The few reform organizations that do exist — such as the National Black Police Association — have failed miserably. If anything, reform groups would benefit from being able to organize without the influence of an overarching union. The same goes for individual officers. Unencumbered by the union apparatus, it would likely be easier to convince those of good conscience to betray their occupation’s prerogatives and fight for radical causes, including the transformation of policing.

Others may concede we shouldn’t equate cops and teachers and that reform is unlikely to come from the men in blue themselves, but still think it wise to house police unions under labor’s tent — the better to moderate their most reactionary impulses. And to be sure, the largest and arguably most egregious police union — the Fraternal Order of Police, which boasts more than 325,000 members — isn’t affiliated with the AFL-CIO.

But corralling them into the labor federation would lend them a legitimacy that they both don’t deserve and would be injurious to social movement unionism. Termites of the labor movement, more influence for police unions would threaten the very foundation of progressive unionism. The most spick-and-span cop union still takes as its mission the advancement of police and policing as an institution.

Last September, in the wake of mass protests in Ferguson, AFL-CIO President Richard Trumka noted that Darren Wilson and Michael Brown’s mother had something in common: they were both union members. “Our brother killed our sister’s son,” Trumka said in a speech at the Missouri AFL-CIO convention, “and we do not have to wait for the judgment of prosecutors or courts to tell us how terrible this is.”

Trumka’s intent, of course, was to telegraph empathy and signal the AFL-CIO’s commitment to racial justice, and the speech did contain plenty of commendable denunciations of racism and police brutality. But the moment underscored the problem with inviting agents of oppression into a movement founded on fighting it. Wilson, though not represented by a union affiliated with the AFL-CIO, was still counted as an upstanding union member.

As the UC academic workers recognize, there needs to be a clearer line of delineation. A labor movement that values the Michael Browns and Freddie Grays and Sandra Blands has no room for police unions.