Section 281

It is lawful for any person to use such force as is reasonably necessary in order to prevent the commission of an offence which is such that the offender may be arrested without warrant; or in order to prevent any act from being done as to which he believes, on reasonable grounds, that it would, if done, amount to any such offence; or in order to prevent a person whom he believes, on reasonable grounds, to be of unsound mind, from doing violence to any person or property.