There are two distinct aspects to the meaning of the word “law” when used today to refer to rules for governing how people choose to act. One aspect is rooted in the presumed source of law; the other aspect is rooted in the presumed function of law. Most people mistakenly take for granted that both aspects must be present for a rule to be law.
The first aspect is that the rule be promulgated and enforced by – or at least enforced by – the state. The second aspect is that the rule be meant to modify, through the use of incentives, the way people act. (The incentives are understood usually to be negative ones, such as “If you kill an innocent person you will pay with your life by being executed.” Such incentives can, of course, be imagined to be positive ones, such as “If you never kill an innocent person during your life the government will give $25,000 to your heirs upon your death.”)
I believe that the first aspect of the popular meaning of the word “law” is distorted and, hence, should be abandoned. Just because the state claims for itself the exclusive power to create law, and just because it monopolizes (usually through the use of force) the power to enforce some of the most important rules of conduct (such as those against murder), and just because we are accustomed to calling the rules promulgated by the state “law,” does not mean that law necessarily is that set of rules, and only that set of rules, handed down by and enforced by the state.
Historical examples abound both of
(1) rules that the state duly promulgates and presumably intends to enforce but which are disobeyed so widely that these edicts cannot be legitimately said to be “law” that governs behavior (for example, 55mph speed-limits on U.S. Interstate highways), and
(2) rules that people obey that are neither created by nor enforced by the state (for example, the first-come, first-served rules for queuing, and, more formally, the lex mercatoria).
I believe that the functional aspect of law is the relevant one. I therefore argue that the term “law” correctly refers to all sets of rules that modify humans’ choices of actions, regardless of whether or not the state promulgated the rules, codified the rules, actively enforces the rules, or even recognizes the legitimacy of the rules. If the rules generally affect human behavior, the rules are law. (These rules might also be recognized to be morals and norms – but they are also law.) Whether or not the state is involved is irrelevant. Also irrelevant is the severity of the punishment for violations of the law. Laws whose violations are less costly to society naturally should be enforced with less-severe penalties. Punish cold-blooded murders severely; punish people who violate the laws of grammar much more lightly (say, with only a snarky critical whisper).
As regular readers of this blog know, I go even further and call law only those rules that evolve decentrally from on-going human interactions. The state might later codify and – or or – take over some or all of the responsibility for enforcing such rules. Rules designed by the state – rules that do not emerge spontaneously from on-going human interactions – are properly called “legislation.”