Hum, I don't know the US law, but in my country the same kind of law is applyable.

As I was instructed when I had received first aid courses, you should first try to use pressure. If it's not enough to stop the bleading you should consider using a tourniquet.

Please note also the time where the tourniquet where put in place, it's importent for doctors. also please note that she tourniquet should only be removed by a doctor ;).

In any case, the tourniquet should be the last attempt