36 Whenever the general interest or any particular class suffers, or is threatened with harm, which can in no other way be met or prevented, the public authority must step in to deal with it. Now, it is to the interest of the community, as well as of the individual, that peace and good order should be maintained; that all things should be carried on in accordance with God's laws and those of nature; that the discipline of family life should be observed and that religion should be obeyed; that a high standard of morality should prevail, both in public and private life; that justice should be held sacred and that no one should injure another with impunity; that the members of the commonwealth should grow up to man's estate strong and robust, and capable, if need be, of guarding and defending their country. If by a strike of workers or concerted interruption of work there should be imminent danger of disturbance to the public peace; or if circumstances were such as that among the working class the ties of family life were relaxed; if religion were found to suffer through the workers not having time and opportunity afforded them to practice its duties; if in workshops and factories there were danger to morals through the mixing of the sexes or from other harmful occasions of evil; or if employers laid burdens upon their workmen which were unjust, or degraded them with conditions repugnant to their dignity as human beings; finally, if health were endangered by excessive labor, or by work unsuited to sex or age - in such cases, there can be no question but that, within certain limits, it would be right to invoke the aid and authority of the law. The limits must be determined by the nature of the occasion which calls for the law's interference - the principle being that the law must not undertake more, nor proceed further, than is required for the remedy of the evil or the removal of the mischief.
Source: Rerum Novarum (Vatican.va)