Consider two workers, write the authors of new research circulated by the National Bureau of Economic Research. These workers have identical productivity, but one has less bargaining power with her boss than the other. The worker with less bargaining power is more vulnerable to the employer’s whims and less able to fight back against them. She’ll have lower pay, of course, but that’s not her only problem.

An employer might claim greater value from the employment relationship both by paying lower wages and by violating the worker’s labor rights, such as requiring work in unsafe or unhealthy conditions (OSHA), shorting on overtime pay (WHD), or discouraging union organizing by threatening to fire union sympathizers (NLRB).

Low pay and violations of her rights: the two conditions go hand in hand. That’s the conclusion Ioana Marinescu, Yue Qiu, and Aaron Sojourner reach in their paper, “Wage Inequality and Labor Rights Violations.” As Marinescu told MarketWatch, the findings suggest that prior research on wage inequality “understates the true level of inequality since workers who get paid less are more likely to have their rights violated.”