Historians have long used the archives of major institutions to shed light on medieval society, but in more recent decades the focus has turned towards the proliferation of legal documentation possessed by those lower down the social order and the increasing penetration of legal processes into their everyday lives. Yet, in recapturing this world, there is a danger that we take for granted the immense documentary power of a large institutional repository. This article follows several legal conflicts across the fourteenth and early fifteenth centuries involving the monks of Durham Priory to demonstrate the extent of this archival culture, showing how they turned to their vast array of documentary evidence for information about those who had incurred their wrath. Using their archives, they traced the descent of holdings, the offices held by key individuals, and previous payments in account rolls, all in a bid to demonstrate their rights, the ‘abuses’ of officials, and to counter legal opposition. Not content, the monks then compiled this evidence into an alternative narrative of events that questioned previous legal proceedings and ceremonies, constructing an institutional memory that saw contradictory documentation as ‘entirely most falsely forged’.