At common law the defence of self-defence operates in three spheres. It allows a person to use reasonable force to:
[color=rgba(0, 0, 0, 0.68)](a) Defend himself from an attack.
[color=rgba(0, 0, 0, 0.68)](b) Prevent an attack on another person,
[color=rgba(0, 0, 0, 0.68)](c) Defend his property.
[color=rgba(0, 0, 0, 0.68)]喺公安條例入面:
本條並不減損任何人為防衞人身或財產安全而使用武力的合法權利。