Oh. Wow. In the US, unless you're part of a union that has a contract with your employer, you can be fired outright for any reason at all. And many states don't allow those sorts of union contracts. (Edit: that's not entirely true, but that's the ultimate result of the laws involved. For more information, see Right-to-work law.) Salaried employees are not restricted as to the number of hours that they can be required to work, at least nothing as low as 48.

If you felt as if you were unfairly terminated, you can sue your former employer, but you've already lost your job and you'd better get on to finding a new one.