Whether self defence is taken in the context of the basic interpretation, or by the more complex martial arts defence systems, the legal basis of the term as interpreted by both courts and police is “necessary force”.
Basically this means that whatever you do it is your responsibility and you will have to justify any injuries you may cause. In law you are entitled to defend yourself, your spouse and your family from an attack and to use whatever force is necessary in the prevailing circumstances to prevent serious physical injury. You are also entitled to defend your property and prevent an attack on another person. No one can dictate what you can or cannot do in any hard and fast manner as all situations will vary and what may be termed as necessary force in one set of circumstances may be regarded as excessive in another even though the same method was of defence was used in both cases.
By relating the legal position to Jujutsu we can see that a lot of moves learned by students of Jujutsu could very easily be regarded as excessive force if taken to their conclusion. As with any martial art, Jujutsu is a discipline and part of that discipline is designed to create self discipline in the student, therefore the first consideration must be to walk away. If this is not possible then the second consideration must be “to exercise maximum restraint”. No two set of circumstances are the same and there are many variables. The law is not specific, so what in your mind you consider is necessary force and to be perfectly justifiable might not be considered as such by a court at a later date that will consider the facts of what happened in an atmosphere that is totally different from that in which the incident occurred.
There are several circumstances where the use of necessary force may be regarded in a more lenient light by a court or the police; these are,
1. To apprehend or assist in the apprehension of someone caught in the act of committing a crime, force must only be necessary to apprehend the culprit.
2. When defending yourself against an attacker who is armed with a weapon.
3. When having been attacked and received injury, self defence techniques are used on the attacker to prevent further injury.
4. In the case of a woman being attached by a male attacker then a greater degree of force and injury on the attacker would be tolerated.
A court will expect a greater degree of self restraint from a student who is highly trained in any martial art particularly Jujutsu. Don’t get trapped into misusing your knowledge.