H. L. A. Hart (1907-1992) practiced law for a time before WWII but after the war taught at Oxford, first in philosophy and then in law as Professor of Jurisprudence (1952-1968). Philosophical work at Oxford after WWII was heavily influenced by the thought of Ludwig Wittgenstein (1889-1951), and Hart’s work on the philosophy of law is no exception, exhibiting a central concern with language and, especially, with the complexity of its ordinary use.
The Concept of Law grew out of Hart’s lectures in an undergraduate course on the subject at Oxford. His first two chapters present first his own understanding of the task of the philosophy of law and then give an account of the motivation for Austin’s views, which he goes on to criticize in chs. 3 and 4 (which are directed, respectively, at the ideas of “command” and “sovereign”). Although chs. 1 and 2 are well worth reading, you can get a sense of his positive account of Austin by looking at just the last paragraph of ch. 2 (p. 25).
Although Hart’s target in ch. 3 is Austin, he also has in mind the views of others, most notably Hans Kelsen (1881-1973). Kelsen was an Austrian who was influential in Europe before the rise of Nazism. He moved to the United States in 1940 and spent the rest of his life here. He was a legal positivist whose views are roughly midway between those of Austin and Hart. (Many of Hart’s references to figues like Kelsen do not appear explicitly in the text but instead in the section of notes at the end, pp. 277-307. Hart will not refer you to these, so you will have to seek them out; and it can be worth doing so since many go well beyond bibliographic references to explain more fully points made in the main text.)
• Hart’s main point in ch. 3 § 1 is that, if we think of law as consisting of rules that impose duties, we may miss other sorts of law, most importantly rules that confer powers. In subsections of this section, Hart discusses examples of the latter sort of rule, considers two attempts to reduce rules of that sort to duty-imposing rules (i.e., to show that they are only apparently different from duty imposing rules), and considers what can be said against even attempting such a reduction. Look at the range of examples surveyed on pp. 27-33 but also at the explicit comparison of the two sorts of rule in the final paragraph of the subsection (pp. 32f). (Hart goes on in two subsections that I haven’t assigned to describe and respond to attempts by Austin and Kelsen to reduce power-conferring rules to duty-imposing rules.)
• In reading ch. 3 §3, think how Austin’s idea of a tacit order is supposed to work and why Hart thinks it doesn’t, think about the significance of custom (which is important for Hart’s own positive view), and notice Hart’s summary of the whole chapter’s main points (in a different order) in the next-to-last paragraph (p. 48).
• In §1 of ch. 4, Hart presents one of his criticisms of Austin’s use of the idea of habitual obedience. You should think through the problems that Hart takes the right of succession of sovereigns to raise for Austin’s idea that habitual obedience is the basis for sovereignty (there is a summary on pp. 59f). But also think about Hart’s discussion of conditions for the existence of rules on pp. 55-57 and about the idea of an “internal aspect” of rules; it will be developed further in later chapters.
We won’t look at the remaining sections of ch. 4; but, although Hart does not summarize the points made in this chapter as he did in ch. 3, you can find a statement of its general moral in the paragraph at the middle of p. 77.