any labour required in consequence of the sentence or order of a court;

any labour required of a member of a disciplined force in pursuance of his duties as such or, in the case of a person who has conscientious objections to service in a naval, military or air force, any labour that that person is required by law to perform in place of such service;

labour required of any person while he is lawfully detained that, though not required in consequence of the sentence or order of a court, is reasonably necessary in the interests of hygiene or for the maintenance of the place in which he is detained; or

any labour required during a period of public emergency or in the event of any other emergency or calamity that threatens the life or well-being of the community, to the extent that the requiring of such labour is reasonably justifiable, in the circumstances of any situation arising or existing during that period or as a result of that other emergency or calamity, for the purpose of dealing with that situation.