From UK law
"Use of Force against Those Committing Crime
Prosecutors should exercise particular care when assessing the reasonableness of the force used in those cases in which the alleged victim was, or believed by the accused to have been, at the material time, engaged in committing a crime. A witness to violent crime with a continuing threat of violence may well be justified in using extreme force to remove a threat of further violence.
In assessing whether it was necessary to use force, prosecutors should bear in mind the period of time in which the person had to decide whether to act against another who he/she thought to be committing an offence.
The circumstances of each case will need to be considered very carefully.
See
Public Interest Use of Force against Those Committing Crime, below in this chapter
In
R v Martin (Anthony) [2002] 1 Cr. App. R. 27, the Court of Appeal held that whilst a court is entitled to take account of the physical characteristics of the defendant in deciding what force was reasonable, it was not appropriate, absent exceptional circumstances which would make the evidence especially probative, to take account of whether the defendant was suffering from some psychiatric condition.
Final Consequences
The final consequences of a course may not be relevant to the issue as to whether the force used was reasonable. Although, the conduct of the suspect resulted in severe injuries to another or even death, this conduct may well have been reasonable in the circumstances. On the other hand, the infliction of very superficial or minor injuries may have been a product of simple good fortune rather than intention.
Once force was deemed to be unreasonable, the final consequences would be relevant to the public interest considerations.
Burden of Proof
The burden of proof remains with the prosecution when the issue of self-defence is raised.
The prosecution must adduce sufficient evidence to satisfy a jury beyond reasonable doubt that the defendant was either:
- not acting to defend himself/herself or another; or
- not acting to defend property; ornot acting to prevent a crime or to apprehend an offender; or
- if he was so acting, the force used was excessive.
Prosecutors should take special care to recognise, and ensure a sufficiency of evidence in, those cases where self-defence is likely to be an issue. "