In the U.S., it is against state law to fire anyone for a workplace injury or anyone who has an open case for a federal DOL injury [http://painstopmd.com/waco-tx-dol-workers-comp-doctor/]. However, you did say that he hurt himself during his probationary period and they claim their reasoning to be that he didn’t meet the job requirements. It seems like a really big risk for a company to take considering he injured his back and received treatment within his probationary period. There must be something that can be done about these types of cases, I would think anyway.