The late-thirteenth-century con􀀀ict between PopeBoniface VIII and the French King Philip IV providedthe context within which the medieval idea ofsovereignty fully crystallized. It began innocentlyenough. In the later decades of that century, KingPhilip began taxing members of the French clergy tohelp 􀀀nance his war against England. While formallyprohibited by a decree of the Fourth Lateran Council(1215), the papacy had long acquiesced in thepractice of French lay rulers taxing their clergywithout explicit papal authorization, mainly becauseit depended on French support in its perennialcon􀀀icts with the Holy Roman Emperor. In 1296,however, Boniface decided to apply the prohibitionto France as well as the Empire. Historians disagreeas to why he made this fateful decision. On the onehand, there are those who assert that the new popewas simply acting on the basis of his 􀀀rmly heldhierocratic belief that ecclesiastical power wassuperior to temporal power. On this view, Phillip'sdecision to tax the French Church presented Bonifacewith his 􀀀rst real opportunity to assertecclesiastical authority—an opportunity he seizedenthusiastically.

O n the other hand, some emphasize the role played byBoniface's ardent desire to launch a crusade torecover the Holy Land. From this perspective, thepope's decision had less to do with his hierocraticvision and more with his belief that clerical taxrevenues should not be used to sustain a war betweenChristian rulers, especially when that war waskeeping those rulers from “taking the cross” and􀀀ghting to liberate the Holy Land. Whatever hismotivation, in February 1296 Boniface issued thebull Clericis laicos,expressly prohibiting all lay rulers—including“emperors, kings or princes, dukes, counts orbarons, podestas, captains or o􀀀cials or rectors—bywhatever name they are called…”—from exacting orreceiving ecclesiastical revenues or propertywithout prior authorization from the Apostolic See.The bull also speci􀀀ed the consequences of suchunauthorized taxation of the clergy: guilty persons were subject to thepunishment of excommunication; guilty corporations were subject tothe punishment of interdict.

Perhaps predictably, Philip responded swiftly to whathe perceived to be Boniface's threat to both hispolitical authority and his ability to prosecute hiswar against England.