text:  Netta Ulibi, NPR News. Prison labor has evolved into a multi-billion dollar industry, but a federal judge in Louisiana is ordering the state to take steps to make sure the health of prisoners toiling in the fields of a former plantation are protected. U.S. District Court judge this week ruled that prison workers face substantial risk of injury or death by being forced to work outside in the summer heat. The judge gave the state seven days to provide a plan for improving work conditions for inmates at the Louisiana State Penitentiary.