13 Moreover, the highest duty is to respect authority, and obediently to submit to just law; and by this the members of a community are effectually protected from the wrong-doing of evil men. Lawful power is from God, "and whosoever resisteth authority resisteth the ordinance of God' ;(6) wherefore, obedience is greatly ennobled when subjected to an authority which is the most just and supreme of all. But where the power to command is wanting, or where a law is enacted contrary to reason, or to the eternal law, or to some ordinance of God, obedience is unlawful, lest, while obeying man, we become disobedient to God. Thus, an effectual barrier being opposed to tyranny, the authority in the State will not have all its own way, but the interests and rights of all will be safeguarded - the rights of individuals, of domestic society, and of all the members of the commonwealth; all being free to live according to law and right reason; and in this, as We have shown, true liberty really consists.
Source: Libertas (Vatican.va)