Interest in the problem of Roman law in Henry de Bracton's De legibus et consuetudinibus Angliae has recently started up with renewed vigor and with increasing emphasis upon the European rather than insular character of his treatise and upon the necessity of studying it ‘within the framework of the European legal (especially legistic and canonistic) literature of his time.’ But among the important elements of Roman law in Bracton the familiar maxim, ‘quod omnes similiter tangit, ab omnibus comprobetur’ (the words of Justinian, C. 5, 59, 5 §2), has been overlooked. In this study I wish to show how Bracton was influenced by the maxim (henceforth referred to simply as q. o. t. — quod omnes tangit), and how his acceptance of it may have some significance for its appearance in royal writs by which communities were summoned to send representatives to Parliament. For towards the end of the thirteenth century and later, the kings of England and France, when they needed extraordinary taxes or national support in quarrels with Pope Boniface VIII and consequently had to obtain the consent of great nobles, prelates and communities of lesser free men, sometimes stated in the preamble to summonses to an assembly that the cause of the convocation was a serious or difficult business (ardua negotia) touching (contingentia or tangentia) both king and kingdom. The presence of tangere or contingere in a context of the kind resulted, although students of representation have not observed it, from the influence of q.o.t. as an equitable principle in legal procedure—this will become apparent after the legal meaning and the terminology current in the thirteenth century are examined.