Prison labour is a form of modern American slavery used by multiple large corporations across the world. Under the 13th amendment to the United States Constitution, slavery was merely reformed rather than abolished.

An example of one of the most extreme cases of prison labour happens in Texas and Florida, where prisoners are forced to work in fields without any pay. Companies like McDonald's, Wal-mart and many more use slave labour to cut down on production costs despite being more than able to use other ways. Racial justice in the USA cannot be achieved until prison labour is abolished completely. 

A full list of companies that use prison labour can be found here: https://www.buycott.com/campaign/companies/504/boycott-companies-that-use-prison-labor