The thesis compares John Finnis' theory of law against the traditional natural law theory of St. Thomas Aquinas. The thesis demonstrates that there are a number of differences between Aquinas' philosophy of natural law and Finnis' philosophy of natural law. Finnis's philosophy of law, although formulated in opposition to the dominant positivist tradition in Anglo-Saxon countries and full of appreciation for Aquinas's achievements, is, after all, distinctly different from St. Thomas's idea, which has a certain metaphysical dimension.