In his concise examination of the social and philosophical bases of law, H. L. A. Hart states that one main reason he wrote the book is to connect the definition of law, about which most people cannot agree, to the practical aspects of law, which does not seem as challenging to understand, or at least to cite. The vast array of definitions of what constitutes law—as opposed to distinct laws—is dauntingly wide. He does not think that this means that most definitions are wrong, however; the core values that make up law will vary among societies. In contrast, many members of a given society will know some of its laws, or at least how to learn what those laws are.

Few Englishmen are unaware that there is a law forbidding murder, or requiring the payment of income tax, or specifying what must be done to make a valid will. Virtually everyone except the child or foreigner coming across the English word “law” for the first time could easily multiply such examples . . . .

Hart explains a fundamental principle of law to be that of “sovereignty.” This concept includes ideas about order, authority, and allegiance. He is not referring specifically to the centralized authority of a monarchy or similar system, however; the sovereignty concept applies equally well in a democracy. The concept he presents is the “doctrine of sovereignty.”

The doctrine asserts that in every society, where there is law, there is ultimately to be found latent beneath the variety of political forms, in a democracy as much as in an absolute monarchy, this simple relationship between subjects rendering habitual obedience and a sovereign who renders obedience to no one.

The reasons that this concept can apply in a democracy include the idea that the sovereign, or entity above the law, is the entity that creates laws and imposes limitations.

He creates law for others and so opposes legal duties or limitations upon them whereas he is said himself to be legally unlimited and illimitable.

The next, related questions that arise, for Hart, are the determination of who obeys such law and how they are encouraged to do so. These ideas include the “habit of obedience.” More importantly, Hart argues, is the understanding of legitimacy that continues regardless of the person occupying the condition of sovereignty. Law, he shows, is a concept that continues regardless of any individual’s status in regard to sovereignty. Beyond the habit of obedience, there must be social rules to which members of a society adhere. Rather than a habit, which is reducible to observed behavior, rules can prescribe enforceable behavior.

If a social rule is to exist some at least must look upon the behavior in question as a general standard to be followed by the group as a whole. A social rule has an “internal” aspect in addition to the external aspect which it shares with a social habit and which insists in . . . regular uniform behavior . . . .

Such rules can be separated from habit by the analogy of a game—in his choice, chess, in which players follow rules. The internal aspect includes cohesiveness in the attitude of acceptance, as all must agree to comply to using the regular stand to comply with behavior, rather than merely to observe it.