Justice and injustice were subjects of ongoing debate in medieval Europe. Received classical and biblical models both influenced how these qualities of moral and political life were perceived, discussed and acted upon. Important among these influences was the anonymous seventh-century Irish text, On The Twelve Abuses of the Age, a biblically-inspired discussion of the moral duties particular to each sector of society. This volume probes its long influence, and its interaction with the revival of classical ideas. By bringing together scholars of political thought and practice, in lay and religious contexts spanning the seventh to fourteenth centuries, this volume crosses boundaries of periodisation, discipline and approach to reflect upon the medieval evolution of concepts of injustice and means of redress. Contributions address how ideas about justice and injustice were discussed among scholars and theologians, and how those ideas were translated into action through complaint and advice throughout the medieval period.