The following extract is from Thomas Hobbes’ The Elements of Law:
In the state of nature, where every man is his own judge, and differeth from other concerning the names and appellations of things, and from those differences arise quarrels, and breach of peace; it was necessary there should be a common measure of all things that might fall in controversy; as for example: of what is to be called right, what good, what virtue, what much, what little, what meum and tuum, what a pound, what a quart, &c.
For in these things private judgments may differ, and beget controversy. This common measure, some say, is right reason: with whom I should consent, if there were any such thing to be found or known in rerum natura. But commonly they that call for right reason to decide any controversy, do mean their own.
But this is certain, seeing right reason is not existent, the reason of some man, or men, must supply the place thereof; and that man, or men, is he or they, that have the sovereign power, as hath been already proved; and consequently the civil laws are to all subjects the measures of their actions, whereby to determine, whether they be right or wrong, profitable or unprofitable, virtuous or vicious; and by them the use and definition of all names not agreed upon, and tending to controversy, shall be established. As for example, upon the occasion of some strange and deformed birth, it shall not be decided by Aristotle, or the philosophers, whether the same be a man or no, but by the laws.