Prevention of Crime or Assisting in the Arrest of Offenders

Prevention of Crime or Assisting in the Arrest of Offenders 

Under section 101A of the Criminal Procedure Ordinance (Cap. 221), a person may use such force as is reasonable in the circumstances in the prevention of crime, or in effecting or assisting in the lawful arrest of offenders or suspected offenders or of persons unlawfully at large. 

At common law, a person is entitled to use reasonable force to protect the safety of himself or his property. Section 101A essentially embodies this common law principle. Even as between strangers, there is a general right to prevent the commission of a crime, particularly in cases involving violence or damage to property. Where this defence is raised, it is for the jury to decide whether intervention to prevent the crime was called for, whether the manner of intervention was reasonable, and whether the force used was appropriate. Where the defence has been properly raised on the evidence, the prosecution bears the burden of disproving it beyond reasonable doubt. 

If the defendant honestly but mistakenly believed that force was necessary to prevent crime, protect property or defend himself, the court will assess the reasonableness of the force used on the facts as the defendant honestly believed them to be. In this respect, there is no material difference in the principles applicable to the prevention of crime, the protection of property and self-defence. This does not, however, mean that excessive force thereby becomes acceptable—even on the premise of an honest mistake, the force used by the defendant must still be proportionate to the threat as he subjectively perceived it.