The researchers said one of the most surprising findings was how successful low-wage employers were in pressuring workers not to file for workers’ compensation. Only 8 percent of those who suffered serious injuries on the job filed for compensation to pay for medical care and missed days at work stemming from those injuries.

“The conventional wisdom has been that to the extent there were violations, it was confined to a few rogue employers or to especially disadvantaged workers, like undocumented immigrants,” said Nik Theodore, an author of the study and a professor of urban planning and policy at the University of Illinois, Chicago. “What our study shows is that this is a widespread phenomenon across the low-wage labor market in the United States.”

According to the study, 39 percent of those surveyed were illegal immigrants, 31 percent legal immigrants and 30 percent native-born Americans.

The study found that 26 percent of the workers had been paid less than the minimum wage the week before being surveyed and that one in seven had worked off the clock the previous week. In addition, 76 percent of those who had worked overtime the week before were not paid their proper overtime, the researchers found.

The new study, “Broken Laws, Unprotected Workers,” was conducted in the first half of 2008, before the brunt of the recession hit. The median wage of the workers surveyed was $8.02 an hour  supervisors were not surveyed  with more than three-quarters of those interviewed earning less than $10 an hour. When the survey was conducted, the minimum wage was $7.15 in New York State, $7.50 in Illinois and $8 in California.