It is not required on our state, but mc5aw's advise about vocalizing your warning while on the phone is the same as the LEO instructor's at the CPL class I took. They also stressed the fact that people will keep coming without knowing they're injured for minutes simply on adrenalin. If that worst case happens, the advise is to keep firing at center mass until they go down. The legal aspect of the class is as or more valuable than the shooting skills, especially since every state is different. I highly recommend that you spend the time and money for the training and information. It really helped me process and settle all of those questions.