‘Item they say when the kynge wulle shall be traytours and when he wulle none schalle be none; and that aperuthe wele hidurto’: so ran one complaint of the Kentishmen in 1450. Very likely ‘they’ were the Lancastrian courtiers and the extreme opinions which they held about the king's judicial prerogative were unlikely to have had the unreserved support of the fifteenth-century lawyers. By their complaint the Kentishmen were unwittingly drawing attention to one of the great problems concerning late medieval treason, namely the degree to which the government had to observe accepted precedent and normal legal procedure. In the matter of defining treason the law to be observed was primarily the statute of 1352 and the problem concerns how far the act was covertly altered and extended by judicial construction. The first impression is that the alterations and extensions must have been considerable since the period produced several new types of state trial, different varieties of popular insurrection and a high incidence of summary trials on the battlefield. To these must be added that number of novel crimes and situations which expose the deficiencies of any piece of legislation. On the other hand the development of parliamentary attainder during the fifteenth century might be taken as evidence against this viewpoint since attainder, it is often said, could supplement and afforce the common law and so might do away with the need for construction or alteration. We must remember that in this period the scope of treason was rarely a great constitutional issue, or at least openly so.