Natural Law and Natural Rights by John Finnis

The core of this book is its second Part. In one long movement
of thought, these chapters (III–XII) sketch what the textbook
taxonomists would label an ‘ethics’, a ‘political philosophy’, and a
‘philosophy of law’ or ‘jurisprudence’. We may accept the labels,
as a scholarly convenience, but not the implication that the ‘disciplines’
they identify are really distinct and can safely be pursued
apart. Parts One and Three are, in a sense, outriders. Anyone
interested in natural law simply as an ethics may omit Chapter I;
anyone whose concerns are limited to jurisprudence may omit
Chapter XIII. And those who want to see, in advance, how
the whole study yields an understanding very different from the
accounts of ‘natural law’ in their textbooks of jurisprudence and
philosophy might turn first to Chapter XII, and then perhaps to
Chapter II.