I’ve added a paper which sketches basic points on which classical natural law theory differs from the so-called “new natural law” theory.  Please see under the tabs above, “Scholarship — Articles and Papers.”  The paper is entitled “Some Observations on Natural Law” and is to appear in Diametros, the online journal of the philosophy department of the Jagiellonian University, Krakow.  You may glean the sense of the paper from its opening paragraphs:

According to the New Natural Law (“NNL”) theorists, practical reason as prescriptive is distinct in kind from speculative reason as descriptive; practical reason starts from axioms or first principles that are wholly underived, and which therefore a fortiori are not derived from any truths of speculative reason; these first principles articulate basic human goods; and, moreover, these first principles are directives addressed to the individual engaged in practical reasoning, that he should pursue these goods.

I maintain that for St. Thomas Aquinas, in contrast, practical reason and theoretical reason largely overlap; the first principles on which practical reason relies are in an important sense derived from speculative truths; these first principles do not articulate but rather presuppose basic human goods; and, finally, their form is law-like, that is, they state in the first instance what human beings in general should do, not what some particular, reasoning individual should pursue or do.

I believe that the NNL theory is based on fundamental misunderstandings of the nature of necessity in St. Thomas; the nature of propositions which are “known in themselves” (per se nota); and the nature of fundamental practical reasoning.  Where the NNL differs from St. Thomas, according to the correct interpretation, as understand it, I regard St. Thomas as providing a better framework for the development of accounts of natural law today.