A landmark class action lawsuit is accusing the for-profit prison company GEO Group of violating federal anti-slavery laws by forcing up to tens of thousands of detained immigrants to work for free, or for as little as $1 a day. The lawsuit was first filed in 2014 and won class action status last week. It accuses GEO Group of forcing people detained at the Denver Contract Detention Facility to work without pay to clean the facility—or face solitary confinement if they refuse. It also accuses GEO Group of breaking Colorado’s minimum wage laws by paying only $1 a day for other work carried out by prisoners inside the jail. GEO Group owns and operates the Denver detention center under a contract with ICE.