In the state of SC is it legal to be fired for not working on your day off?
Did you get fired because they asked you to come in and you said no? Some states are "employ at will" states and, technically, can fire for just about anything. Maryland is like that and I have seen it happen. :-(
It's not legal in any state. A day off implies not working, and you can't get fired if it's your had off.
If you worked it would not be a day off. It would be a workday. Do you get paid for days off?