DENVER — Every day, immigrants are told to clean their living areas in a privately run Colorado detention center or risk being put in solitary confinement. Some also volunteer to do jobs as varied as landscaping, more cleaning and cutting other inmates’ hair, but the pay is always the same – $1 a day.

A group of former detainees says the system borders on modern-day slavery. They are challenging it in federal court and have won the right to sue the Denver-area detention center’s operator on behalf of an estimated 60,000 people held there over a decade.

The former detainees allege the GEO Group is exploiting people in the 1,500-bed center to keep it operating with just one full-time janitor. The company reported $2.2 billion in revenue and had nearly $163 million in adjusted net income last year.

The case could have broad consequences for the private prison industry, which hopes to cash in on demand for more detention space as the Trump administration cracks down on illegal immigration.

Immigration detention centers are roughly the equivalent of jails in the criminal justice system – places where people accused of civil violations of immigration law wait until their cases are resolved. While people convicted of crimes and serving time in prison are often required to work, those held in the nation’s jails generally cannot be forced to work because they have not been convicted, according to the U.S. Justice Department’s National Institute of Corrections.

Courts view immigration detention not as punishment but as a way to keep people from fleeing, said Kathleen Kim, a professor at Loyola Law School in Los Angeles who specializes in immigration law. Forcing detainees to work violates the 13th Amendment, which ended slavery and bars involuntary servitude except for punishment of a crime, she said.

Financially, “this model of operating these facilities very much depends on the labor of the people detained there,” said an attorney for the Colorado detainees, Andrew Free, of Nashville, Tennessee.

GEO says it is only following government policies and wants an appeals court to block the case from proceeding on behalf of everyone held from 2004 and 2014, noting class-action status could lead to additional claims against similar companies.

That’s already started. Another lawsuit filed in May against CoreCivic, the nation’s largest private prison operator, challenges similar labor practices at its San Diego immigration detention center.