Damon Root writes about racism in the labor movement while arguing that liberals often uncritically laud unions as "an unalloyed force for good" while ignoring that "there's an ugly side to the "strength of unions." I think that's sometimes true, but I don't really think this is a fair criticism of Kevin Drum's piece, which acknowledges rather forthrightly that "big unions have plenty of pathologies of their own," but the history of racism in the labor movement is certainly something worth acknowledging. Arguing unions have been a net good for society as a whole doesn't preclude acknowledging their historical faults.
Root writes:
As scholars ranging from the liberal political scientist Ira Katznelson to the libertarian legal historian David Bernstein have now documented, organized labor’s rise to power typically came at the expense of black workers. Consider collective bargaining, the legal arrangement whereby a union selected by a majority of employees receives the monopoly bargaining power to exclusively represent all employees. This valuable union tool first became part of federal law under section 7A of the National Industrial Recovery Act of 1933. Since blacks were barred from the vast majority of unions at that time, collective bargaining served as a de facto ban on all black workers in unionized shops.
I think this is like saying capitalism hasn't been an "unalloyed force for good" for black people because we were once bought and sold as property. The labor movement, like nearly every other institution in American life, was once marred by terrible racism. At the same time, black labor activists like Asa Philip Randolph and Bayard Rustin were among the most prominent leaders of the civil-rights movement. Some of the most racist labor leaders and opponents of organized labor cloaked their racism in "principled" anti-communism, while some communists in the labor movement were among the most committed to integration and equality for black workers. That doesn't automatically make communism good or criticisms of labor unions baseless. You could, like Martin Luther King Jr., be an enthusiastic supporter of workers' right to organize -- including public workers -- while being an outspoken critic of racism in unions.
There was once a great deal of racism in the labor movement, but that doesn't so much indict unions as it does America in general. The problem with the American labor movement in the 1930s wasn't the philosophical and ethical foundation of collective bargaining for workers; the problem was that racism was really pervasive in all aspects of American life.