The Concept of Law is a nonfiction book by legal philosopher and Oxford University professor H. L. A. Hart. The central concept of the book is the examination of legal philosophy within the context of analytical jurisprudence. The other philosophical area that Hart explores is linguistic analysis, which is the definitions of specific legal terms and expressions, and their interpretation depending on context. In fact, linguistic analysis is a method that Hart employs in writing the book. This is because the theory and practice of law are dependent on the interpretation of legal terms, expressions, rulings, and opinions of judges. For this reason, Hart emphasizes the importance of defining terms and how they could be interpreted by lawyers and legal scholars.

The first part of the book is the command theory of law. Hart dedicates a significant portion of the book to critiquing the legal philosophy theories of jurist John Austin, specifically command theory of law. Hart examines the behavioral elements of people's habits, commands, and the nature of obedience, as well as the sociological factors of disobedience. Hart explores the hierarchical nature of commands and how this hierarchy has conditioned people to obey authority figures. Hart concludes that within the context of command theory of law, obedience is caused by threats, such as threats of imprisonment or fines for breaking laws and statutes. However, after outlining the command theory of law as proposed by John Austin, Hart goes on to deconstruct this type of system. Hart details his objections towards Austin's theories. For instance, Hart argues that there are several laws that do not impose duties but do bestow powers to individuals. Hart supports his arguments by citing examples, such as how laws are setting the parameters on how contracts or wills are validated. In the first section, Hart also argues that in command theory of law, lawmakers seemingly receive immunity from the law itself because lawmakers are not specifically mentioned. Law, unlike commands, Hart states, applies to all members of the citizenry, both to lawmakers and common people alike.

The other section of the book is the idea of rule. In this section, Hart makes distinctions of the idea of rule. For instance, Hart outlines the first and secondary rules and their symbiotic dynamic. Hart argues that primary rules—laws imposing duties on society's members—is only plausible in a small-scale organization, such as a tiny tribe, small-sized company, or neighborhood-level politics. Secondary rules—laws that "check" the primary laws—are necessary to offset defects of the primary rules. The section also delves into moral philosophy and how it forms the basis of legal theory. An example of this is the legality of owning slaves in the southern states during slavery era, and the Jim Crow laws of the twentieth century. They were considered legal in the jurisdictions where they were implemented, but they are not what is called natural law, or law based on objective morality (i.e., the immorality of enslaving other human beings).

The last section is the role of judges. In this section, Hart discusses formalism, or mechanical jurisprudence, and the American realist theorists' rule of skepticism. Hart attempts to find a middle path between formalism and the rule of skepticism. In this section, Hart again applies linguistic analysis to present examples for his arguments, such as the term "vehicle" in a statute banning people from parking in public parks. Whilst "vehicle" commonly refers to cars and other automobiles, bicycles and other forms of "vehicles" can be argued to be or not to be excluded from the statute's phrasing.