The present work "Philosophy of Law - Ancient Greek and Modern" by I. Karelis moves on five basic axes. First, it highlights the inseparable interconnection of Philosophy of Law, Ethical Philosophy, and Political Philosophy. Second, it adequately presents the two major schools of thought in Philosophy of Law, natural law and legal positivism. Third, it thoroughly examines ancient Greek and modern philosophy of law. Fourth, it demonstrates and shows that Philosophy of Law permeates almost all branches of Legal Science. Fifth, this work treats specialized issues of Philosophy of Law in a particular way, such as constitutional theory of political disobedience, theory of revolutions, theory and practice of political responsibility, and the issue of the death penalty.