Workers at California warehouses that supply Walmart have filed a federal lawsuit against the companies, saying that they falsify time cards and do not pay minimum wage. Workers say that they are forced to under-record hours, and end up being paid well below minimum wage. The workers also say that there are many safety and health violations in the warehouses. Workers in Chicago are also suing warehouses that supply goods to Walmart, with many of the same charges as the workers in California. Walmart is not named as a defendant in either case.
See "Warehouse workers say abuses are systemic", Lilly Fowler, FairWarning.org, March 4, 2012