"A Treatise of the Laws of Nature", originally titled "De Legibus Naturae", first appeared in 1672 as a theoretical response to a range of issues that came together during the late 1660s. It conveyed a conviction that science might offer an effective means of demonstrating both the contents and the obligatory force of the law of nature. At a time when Hobbes's work appeared to suggest that the application of science undermined rather than supported the idea of obligatory natural law, Cumberland's "De Legibus Naturae" provided a scientific explanation of the natural necessity of altruism. Through his argument for a moral obligation to natural law, Cumberland made a critical intervention in the early debate over the role of natural jurisprudence at a moment when the natural law project was widely suspected of heterodoxy and incoherence. This is the first modern edition of "A Treatise of the Laws of Nature", based on John Maxwell's English translation of 1727. The edition includes Maxwell's extensive notes and appendixes. It also provides, for the first time in English, manuscript additions by Cumberland and material from Barbeyrac's 1744 French edition and John Towers's edition of 1750.