How is the "reasonable force" requirement applied to fights that end up in a grapple?

Question

In the England and Wales ones right to respond to attacks is limited to what is considered "reasonable force". The CPS sum up with a quote from Palmer v R, [1971] AC 814:

It is both good law and good sense that a man who is attacked may defend himself. It is both good law and good sense that he may do, but only do, what is reasonably necessary.

In the case of a fist fight, this is sometimes expressed as if someone punches you, you are allowed to punch them but not allowed to pick up a bottle and hit them with it. However, many fights end up in a grapple on the ground (estimates vary from 42% to 95%). Traditional ways to end a grapple involve causing cerebral hypoxia (chokeholds and strangles) or dislocation (joint locks). These have potentially life changing or life ending consequences, particularly when a submission is impractical. Other techniques such as biting and eye gouging are less likely to be fatal but more likely to cause life changing injuries.

How have court cases interpreted reasonable force in cases where an attacker suffered serious injuries as a result of a fight they initiated ending in a grapple?

Answer 1

The same way it is for every other self-defence case

Whether the force used in a particular case is a matter of fact for the jury to decide, not a matter of law for the judge to dictate. One jury in one case may find that eye-gouging is reasonable, another in a different case may find that it is not. In particular, the jury must decide if the defendant believed their actions were necessary in the circumstances.

In australia the leading case is Zecevic v DPP (1987) 162 CLR 645 which says:

The question to be asked in the end is quite simple. It is whether the accused believed upon reasonable grounds that it was necessary in self-defence to do what he did. If he had that belief and there were reasonable grounds for it, or if the jury is left in reasonable doubt about the matter, then he is entitled to an acquittal. Stated in this form, the question is one of general application and is not limited to cases of homicide.