First, I would remove myself out of their striking range and attempt to verbally de-escalate.
My hospital has a behavioral emergency code, which is responded to by security and psych charge nurse. Our security staff carry tasers, and the RN brings a set of 4-point leathers.
Security RUNS when these are called.
If I were in immediate, life-threatening danger -- e.g. hands around my neck -- I would do absolutely anything to protect myself. My husband has black belts in both kung fu and taekwondo, plus went through RoK army training, and he taught me some serious self-defense techniques... but I'm not above fingers in eyes or a knee in the groin.
If that same person was doing that same action on the street, I would react exactly the same in the hospital.
Legal trouble? People are allowed to protect ourselves -- if the assailant is killed the victim isn't charged with murder, right? Besides, Maslow's Heirarchy people. My need for survival is more than my need to avoid a courtroom.
BUT, my hospital requires "run, hide, or fight" as part of our annual required training. The "fight" option is last resort, but if we need to we fight to prevail (or something to that effect.) Methods -- per hospital's training video -- include throwing heavy and sharp objects. I guess they don't want us to be another St John's?
I do NOT recommend calling a code, unless hitting that button is all you can do. Again, if pt strangling me so can't scream but in reach of the button. 1) the vast majority of violence is not immediately life threatening. We don't need the pharmacist and chaplain and the legion of med students who typically come running to the code; nor do we need the crash cart or heavy LUCAS device. 2) It sounds like this is a frequent occurance on your unit. If each results in a code being called, I can see this becoming a boy who cried wolf situation.