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The principle of volenti non fit injuria, often truncated to 'volenti', can be pleaded as a defence to an action in Tort. The word 'volenti' implies willingness or consent, and the defence implies that the claimant's injuries arose from actions that he entered into voluntarily. The requirements of the defence are interpreted quite strictly by the courts and, for policy reasons, there are circumstances where it cannot be used at all. An employer, for example, cannot use it to defend against an action in Negligence by an employee. A person who goes to the rescue of a victim of the defendent's negligence is not 'volenti', if the circumstances were such as to make a rescue attempt foreseeable. This latter restriction also applies to 'professional rescuers': there is no firemans rule in English law.