Within the State of New York, I am a NYS certified police instructor. My 2 main subjects (amongst others) are the Use-of-Force and Defensive Tactics. Within the State of New York, Use-of-Force is known as Article 35 (statute law).
When martial artists tell me about self defense, they usually argue with me about my instructions. I see it from the eyes of the law and they see it from a hypothetical and academic opinion.
Within the State of New York, you can defend yourself, under certain statute designated crimes, only to the point whereby the threat has stopped. Once that threat has stopped, you must stop.
The State of New York recognizes 2 categories of Use-of-Force. It is either Deadly Physical Force or Physical Force. Deadly Physical Force means that the potential for someone dying is imminent. Physical Force means that it is any force that does not have the potential for someone to die.
How does that work for the practicing martial artist? You can defend yourself, however, you must be careful to not overkill with your techniques. When you have restrained someone, you cannot continue to hurt them.
Criminals will always lie and sue. That is the greatest potential. However, the court system recognizes who is the criminal, who has the criminal history, and who started the sequence of events that led to a self-defense situation.
In regards to Deadly Physical Force, you are an upstanding citizen, minding your own business, attempting to avoid trouble (verbally and/or escaping), and backed into some kinds of position, whereby you can’t safely retreat. You are in fear for your life or another’s whom you are with. You can’t call for the police. Seconds count and the police are minutes away.
Striking, punching, kneeing, and kicking techniques will be highly frowned upon, in the eyes of the law (reality). Grappling and restraining techniques will be looked upon with greater acceptance.
Aikido techniques have worked quite well. Especially the restraining techniques. The trick is not to break bones or cause hospitalizing injuries.