In Henry IV, Parts 1 and 2 Shakespeare provides art image of the unifying function of law in a disjointed society. This article examines the depiction in these plays of an idealised legal system, whose agents subscribe to the axioms of an equitable jurisprudence, in which kings are subject to an unwritten moral law. The central role played by common lawyers to shaping the development of the ancient constitution is considered by reference to two of the principal players in Henry IV, Part 2: the Lord Chief Justice and justice Shallow. The influence of several judges of the early modern period (especially the Lancastrian Chief Justice, Sir John Fortescue) over the depiction of these two characters is analyzed. In the second part of the article the various models of fatherhood offered in the plays are examined The correlation between paternity and the mystical nature of kingship provides the basis for the final section of the article, in which a considered the possible influence of Plowden's Report of the Case of the Duchy of Lancaster over the formulation of Henry IV, Parts 1 and 2.