Continuing with our new series about the best introductory texts in various areas of philosophy, I now invite readers to name what they think are the best introductory texts to any aspect of philosophy of law (e.g., general jurisprudence, philosophy of substantive areas of law, etc.). As before, don't just name a text, but say something about why you think it's particularly notable or valuable. Although you don't have to sign your comment, I do think signed ones will carry more weight with readers.
I'll start off with three suggestions. First, the most important work in general jurisprudence in the last century, H.L.A. Hart's The Concept of Law, was written as an introduction to the subject. Parts of it are nonetheless a bit demanding for a novice, but it is still the best place to start. Brian Bix's Jurisprudence: Theory and Context (now in its 6th or 7th edition, I believe) is more introductory and accessible, and has solid discussions of all the main theories and figures. (About twenty years ago, when I was a visiting professor at Yale, a student plagiarized one of his two final exam essays from the Bix book, which had been listed as a recommended secondary source. I knew something was off because the essay offered a plausible and sophisticated take on some parts of legal positivism, but in terms completely different than my treatment in class! A little digging, and I discovered the sections of the Bix book the student had plagiarized! [Yale Law School didn't want me to fail the student, however...that's another story!]) Mark Murphy's Philosophy of Law: The Fundamentals is more demanding than Bix, but still introductory, and it covers topics in both general and normative jurisprudence. The book is a kind of sustained brief for the natural law approach Murphy favors (and of which he is the leading contemporary defender), but it is generally fair and reliable about other views. Of course, if you're interested in American Legal Realism in particular, there's only one thing you need to read.