There is no better symbol of the common law's evolutionary quandary than the role of so-called great cases. These are cases – Hadley, Donoghue, Hedley Byrne, and their ilk in English private law and Brown, Griswold, Miranda, and their kind in American constitutional law – that are regarded by almost all lawyers as landmarks of the common law tradition. While their precise import and reach are continuously contested, any credible account of the common law has to be centered upon such decisions and must be able to incorporate their authoritative intimations. However, the very existence of such cases and particularly the circumstances of their origin seem to confound the legitimacy of the process that they allegedly anchor and from which they purportedly arise. The sceptical observer might be forgiven for thinking that great cases appear to be less a continuation of legal tradition and more a break with existing traditions; they tend to exemplify a deviation from existing commitments, not a derivation from them. Great cases represent the impressive pragmatic strength of the common law in being able to adapt to fresh challenges and new conditions.