Solidarity has been the foundation of the labor movement since its inception, the idea being that the bosses have all the wealth and power, but the workers have the numbers — so long as they stand shoulder to shoulder. “We must be together; our masters are joined together and we must do the same thing,” said Mother Jones. “They contrive to keep you divided, and as long as you are divided, you will remain where you are, robbed and helpless,” said Eugene V. Debs. “When you unite and act together, the world is yours.”

For as long as socialists and radical unionists have been emphasizing solidarity, bosses have been inventing new ways to divide and conquer the working class. One method that has cropped up in the last couple of decades is mandatory arbitration contracts, which prevent workers from taking their bosses to public court, forcing them instead to settle whatever grievances they may have in a private conference room, via a process tilted in employers’ favor.

Not only that but, as upheld by this week’s Supreme Court case National Labor Relations Board v. Murphy Oil USA, workers have to do it alone. They can’t band together to share legal costs, build a stronger case based on observable patterns in employment practices, or simply give each other courage to endure a long legal battle. They must shoulder the entire burden of the arbitration process by themselves. And as the classic labor movement song asks, “What force on earth is weaker than the feeble strength of one?”