In Oklahoma (and this is a very loose summary of the laws) you can basically put your own rights in the shoes of someone else as far as self defense goes. Meaning, if the girl in this situation would be legally justified in doing something to defend herself, than anyone else who does it for her would also be legally justified. The problem is, you don't know her, so you have NO idea if she would be legally justified. The best you can do is an educated guess, and that would rarely be worth the risk of doing the WRONG thing.
Warhead[97]