Kaarlo Tuori, professor of law, judge, and counsellor to the Constitutional Committee of the Finnish Parliament, has embarked on an ambitious project. He aims to build on the positivism of Kelsen and Hart, but to discover a normative justification of law which goes beyond their limited validity claims. This is the ‘critical’ element which he adds to ‘legal positivism’. Kelsen’s basic norm and Hart’s rule of recognition are irreducible underlying principles. The arbitrary nature of such principles is intellectually suspect, while their internal self referentiality renders them morally sterile. The law is the law — because we recognise it as such or because it is founded on the basic norm — and as such it is valid. This leads to a lack of critical purchase, which is the fundamental drawback of positivism when confronted by natural law or other ethically based theories. Classical mid-twentieth century positivism offers no ethical foundation outside the declared law from which we may criticise unjust laws.