The law of loving one's neighbour as oneself is a "royal law," not as having emanated from God or from Christ as King, still less as being a law which binds even kings, or which makes kings of those who observe it. It is a royal law, as being sovereign over other laws, inasmuch as it is one of those two on which "hang all the Law and the Prophets" (Matt. xxii. 40). Indeed, either of the two may be interpreted so as to cover the whole duty of man. Thus St. Paul says of this royal law, "The whole law is fulfilled in one word, even in this, Thou shalt love thy neighbour as thyself" (Gal. v. 14). And St. John teaches the same truth in a different way, when he declares that "he that loveth not his brother whom he hath seen cannot love God whom he hath not seen" (1 John iv. 20). The expression "royal law" occurs nowhere else, either in the New Testament or in the Septuagint, but it is found in a dialogue entitled Minos (p. 317), which is sometimes wrongly attributed to Plato. It is one which might readily occur to any one as a name for a supreme moral principle.
"Whosoever shall keep the whole law, and yet stumble in one point, he is become guilty of all."[59] The law is the expression of one and the same principle--love; and of one and the same will--the will of God. Therefore he who deliberately offends against any one of its enactments, however diligently he may keep all the rest, is guilty of offending against the whole. His guiding principle is not love, but selfishness--not God's will, but his own. He keeps nine tenths of the law because he likes to do so, and he breaks one tenth because he likes to do so. The fact of his wilful disobedience proves that his obedience is not the fruit of love or loyalty, but of self-seeking. If we ask what his character is, the answer must be, "He is a lawbreaker." These respecters of persons claimed to be observers of the law, because they treated their rich neighbours as they would have liked to be treated themselves. St. James shows them that, on the contrary, they are transgressors of the law, because they pick and choose as to what neighbours shall be treated thus kindly. They keep the law when it is convenient to keep it, and break it when it is inconvenient to keep it. Such keeping of the law is in its essence, not obedience, but disobedience. He who follows honesty only because honesty is the best policy is not an honest man, and he who obeys the law only because obedience suits him is not an obedient man. There is no serving God with reservations. However small the reservation may be, it vitiates all the rest. In order to "_fulfil_ the law" (a rare expression, found only here and in Rom. ii. 27), we must keep it all round, independently of our own likes and dislikes.
St. James is not here countenancing the severity of Draco, that small crimes deserve death, and that there is no worse punishment for great crimes; nor yet the paradox of the Stoics, that the theft of a penny is as bad as parricide, because in either case the path of virtue is left, and one is drowned as surely in seven feet of water as in seventy fathoms. He is not contending that all sins are equal, and that to break one of God's commands is as bad as to break them all. What he maintains is that no one can claim to be a fulfiller of the law in virtue of his extensive obedience so long as there is any portion of the law which he wilfully disobeys. Why does he disobey in this? Because it pleases him to do so. Then he would disobey in the rest if it pleased him to do so. The motive of his conduct is not submission, but self-will. He is in character "a transgressor of the law."