H. L A. Hart, The Concept of Law (Oxford University Press, 2012)—the current edition is the 3rd, but any edition will do

Andrew Altman and Christopher Heath Wellman, “A Defense of International Criminal Law,” Ethics, vol. 115 (2004), pp. 35-67 (on JSTOR at 10.1086/422895)

Ronald Dworkin, “The Model of Rules,” The University of Chicago Law Review, vol. 35 (1967), pp. 14-46 (on JSTOR at 1598947)

Ronald Dworkin, “Hard Cases,” Harvard Law Review, vol. 88 (1975), pp. 1057-1109 (on JSTOR at 1340249)

Kimberly Kessler Ferzan, “Justifying Self-Defense,” Law and Philosophy, vol. 24 (2005), pp. 711-749 (on JSTOR at 30040369)

George Fletcher, “Fairness and Utility in Tort Theory,” Harvard Law Review, vol. 85 (1972), pp. 537-573 (on JSTOR at 1339623)

Wesley Hohfeld, selections from “Some Fundamental Legal Conceptions as Applied in Judicial Reasoning,” The Yale Law Journal, vol. 23 (1913), pp. 16-59 (on JSTOR at 785533)

Oliver Wendall Holmes, Jr., “The Path of the Law,” Harvard Law Review, vol. 10 (1897), pp. 457-478 (on JSTOR at 1322028)

John Rawls, “Two Concepts of Rules,” The Philosophical Review, vol. 64 (1955), pp. 3-32 (on JSTOR at 2182230)

Steven Shavell, “Why Breach of Contract May Not Be Immoral Given the Incompleteness of Contracts,” Michigan Law Review, vol. 107 (2009), pp. 1569-1581 (on JSTOR at 40380344)

Seana Shiffrin, “‘Could’ Breach of Contract Be Immoral?” Michigan Law Review, vol. 107 (2009), pp. 1551-1568 (on JSTOR at 40380343)

“Some ideas of natural law,” selections from Aristotle, Cicero, the Roman jurists, and Aquinas (1up PDF, 2up PDF, booklet PDF)

John Austin, The Province of Jurisprudence Determined

Hugo Grotius, selections from Grotius on the Rights of War and Peace: An Abridged Translation.

John Stuart Mill, selections from On Liberty (1up PDF, 2up PDF, booklet PDF)