A well placed punch to the throat or stomache, however painful, is most likely going to be non lethal
WHOA!!!! HOLD UP!! A well placed punch to the throat is exactly what I would do if my life were in danger. Damage to the thyroid cartilage (adams apple) and/or crychoid (little thing that holds windpipe open above adams apple) is going to cause the the windpipe to close up. The person will asphyxiate in about 3-5 minutes unless a trachiostomy is performed.
If you strike the trachea (windpipe below the adam's apple, above the sternum) it will likely be non-lethal and just cause them to choke and sputter a bit. However, a fist is too big to hit this area, need to use an open hand (web of hand between thumb/index fibger), edge of hand or finger strike to hit the trachea and avoid the thyroid.
This is another reason why it is important to know how to kill with your bare hands...so you also know how
not to by mistake. Also, any time you lay hands on someone, you run the risk of them dying. You punch someone in the solar plexus (non-lethal) but they have a heart problem and this is enough to kill them. Or they fall and fracture their skull. If you were justified in using force, you should be OK, accident. If you punched someone in the stomach because he insulted you, or you could have left, but your ego kept you there...think "manslaughter" charges, even for an accident.
Think this doesn't happen...remember "hockey dad". Reckless coach putting kids in danger. Father of player talks to coach. Father is big man, coach small. Coach is whacko trys to pick fight, father walks away. Coach jumps on back of father as he is walking across the ice, father throws him down on the ice and just shoves him a few times. Problem is, the other man's skull is hitting a hard surface with each shove, brain accelleration, subdural hemotoma, concussion leading to coma and death. The dad had no idea the trauma he was inflicting, now one man is dead, the other in prison for manslaughter.
I know how to cause this type of injury, if my life is in danger, grab his head and slam it into the concrete. On the other hand, if it is some drunk nut that I can handle, I know to say; grab his arm, yank him on his stomach and put my knee in his back holding him for the police.