Over its long history, the American labor movement has displayed a remarkably rich vocabulary for shaming those deemed traitors to its cause.

Some insults, such as “blackleg,” are largely forgotten today. Others, such as “stool pigeon,” now sound more like the dated banter of film noir. A few terms still offer interesting windows into the past: “Fink,” for example, was used to disparage workers who informed for management; it seems to have been derived from “Pinkerton,” the private detective agency notorious for strikebreaking during mass actions like the Great Railroad Strike of 1877.

No word, however, has burned American workers more consistently, or more wickedly, than “scab.”

Any labor action today will inevitably lead to someone getting called a scab, an insult used to smear people who cross picket lines, break up strikes or refuse to join a union. No one is beyond the reach of this accusation: United Auto Workers President Shawn Fain called former president Donald Trump a “scab” in August 2024, after Trump suggested to Elon Musk that striking workers at one of his companies ought to be illegally fired.

While working on my book “Sellouts! The Story of an American Insult,” I discovered that labor’s scabs were among the first Americans identified as sellouts for betraying their own.

Reinforcing class solidarity

The use of scab as an insult actually dates to Medieval Europe. Back then, scabbed or diseased skin was widely seen as the sign of a corrupt or immoral character. So, English writers started using “scab” as slang for a scoundrel.

In the 19th century, American workers started using the word to attack peers who refused to join a union or worked when others were striking. By the 1880s, periodicals, union pamphlets and books all regularly used the epithet to chastise any workers or labor leaders who cooperated with bosses. Names of scabs were often printed in local papers.

Scab likely caught on because it directed visceral disgust at anyone who put self-interest above class solidarity.

Many of labor’s scabs clearly deserved the label. During a strike of Boston railroad workers in 1887, for instance, the union bombarded its chairman with cries of “traitor” and “scab” and “selling out,” because he gave in to company demands prematurely, just as the union’s funds were also mysteriously depleted.

The most powerful expression of this shame comes from the pen of Jack London. Best remembered today for adventure tales such as “White Fang,” London was also a socialist. His popular 1915 missive “Ode to a Scab” captures the venomous contempt many have felt about those who betray their fellow workers:

“After God had finished the rattlesnake, the toad, and the vampire, He had some awful substance left with which He made a scab… a two-legged animal with a corkscrew soul… Where others have hearts, he carries a tumor of rotten principles… No man has a right to scab as long as there is a pool of water deep enough to drown his body in.”

In 1904, however, London had written a longer and less famous essay, “The Scab.” Instead of shaming scabs, this essay explains the conditions that drive some workers to betray their own.

“The capitalist and labor groups,” London writes, “are locked together in a desperate battle,” with capital trying to ensure profits and labor trying to ensure a basic standard of living. A scab, he explains, “takes from [his peers’] food and shelter” by working when they will not. “He does not scab because he wants to scab,” London insists, but because he “cannot get work on the same terms.”

Rather than treat scabs as vampire-like traitors, London asks his readers to see scabbing as a moral transgression driven by competition. It is tempting to imagine society as “divided into the two classes of the scabs and the non-scabs,” London concludes, but in capitalism’s “social jungle, everybody is preying upon everybody else.”

Driven to scab

London’s words ring with a harsh truth, and we can illustrate his point by looking at the discomforting status of Black strikebreakers in American labor history.

During their heyday from the 1880s through the 1930s, major labor organizations such as the Knights of Labor and American Federation of Labor did include some Black workers and at times preached inclusion. These same groups, however, also tolerated openly racist behavior by local branches.

Historian Philip S. Foner tells the story of Robert Rhodes, a union bricklayer in Indiana whose “white union brothers refused to work with him.” The Bricklayers and Masons International Union of America did have a fine of US$100 for such discriminatory practices, but Rhodes was stymied in efforts to get any money, and his racist co-workers punished him for trying. He ended up being accused of “scabbing” by the union, and, in a brutal irony, fined. Rhodes quit and changed his career.

Civil rights activist W.E.B. Du Bois once noted that among the major working-class trades in America only longshoremen and miners welcomed Black workers. In most fields, they had to try to join unions that were often implicitly – if not explicitly – segregated.

To find work as masons, carpenters, coopers – or any other skilled trades dominated by unions that would often discriminate based on race – Black laborers often had to work under conditions that others would not tolerate: offering their services outside the union, or taking over work the union had done while its members were striking.

In short, they had to scab.

Class and race collide

It shouldn’t be hard to see the competing moral claims here. Black workers who had struggled with racial discrimination claimed an equal right to work, even if this meant disrupting a strike. Unions saw this as a violation of working-class solidarity, even as they overlooked discrimination within their ranks.

Managers and corporations, meanwhile, exploited this racial friction to weaken the labor movement. With tensions high, brawls often broke out between Black strikebreakers and white strikers. An account of the 1904 Chicago miners’ strike noted, “some one in the crowd yelled ‘scab,’ and instantly a rush was made for the negroes,” who fought back the mob with knives and pistols before city police intervened.

As this ugly pattern repeated itself, a stigma began to cling to Black workers. White laborers and their representatives, including American Federation of Labor founder Samuel Gompers, often called Black people a “scab race.”

In reality, Black workers were just a small percentage of strikebreakers. Most often, strikebreakers were white immigrants, who, like their Black counterparts, could face discrimination by unions. Black Americans also had a long history of labor activism, struggling for union membership, improved working conditions and better wages in cities such as New Orleans and Birmingham.

In his 1913 essay “The Negro and the Labor Unions,” educator Booker T. Washington urged unions to end their discriminatory practices, which forced Black Americans into becoming “a race of strike-breakers.” Nonetheless, this racial stigma persisted. Horrendous racial violence in the “Red Summer” of 1919 followed close on the heels of the Great Steel Strike, during which nonunion Black workers had been called in to keep steel production humming along.

Preventing fissures among workers

While terms like “scab” and “sellout” have often been used to reinforce labor unity, these same terms have also worsened divisions within the movement.

It’s too reductive, then, to simply shame scabs as sellouts. It’s important to understand why people might be motivated to weather scorn, rejection and even violence from their peers – and to take steps toward removing that motive.

In 2024, Canada’s Parliament passed landmark “anti-scab” legislation, which prohibits 20,000 employers from bringing in replacement workers during a strike.

This law will not only force companies to listen to their workers’ needs during a time of crisis, it will also create fewer divisions within the labor movement – and fewer opportunities for any worker to become a scab.

Ian Afflerbach does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.