This book offers a close reading of key texts of the Holy Catholic League that justified the tyrannicide of Henri iii and formed the cornerstone of the League's ‘resistance theory’. The expression ‘resistance theory’, frequently used in the historiography, implies that the League's arguments for the deposition of Henri iii owed an intellectual debt to the Calvinist Monarchomachs that it refused to acknowledge for obvious partisan reasons. Zwierlein questions the assumption that the League merely ploughed a furrow first traced by Calvinism through a careful reconstruction of the intellectual and chronological origins of these texts. Key sections of De justa populi gallici ab Henrio tertio defectione and De justa Henrici tertii abdicatione are reproduced and translated in the appendix, listing all the manuscript and printed editions consulted for the elaboration of this partial critical edition. As the title suggests, this book reconstructs an intellectual world that is often left out of the historiography, a political thought that had its own identity and coherence, distinct and in parallel with Protestant ‘resistance theory’. It forms part of a reassessment, if not a rehabilitation, of the League's intellectual legacy that was inaugurated by Robert Descimon and José Javier Ruiz Ibanez in their Les Ligueurs de l'exil (Paris 2005) that sought to redeem it from the ‘dustbin of history’. The controversial figure of Jean Boucher, to whom many of these texts were attributed, is key to this reassessment not least because he continued vigorously to promote this intellectual agenda while in exile in the Spanish Netherlands. Zwierlein demonstrates that the League owed a great deal more to the School of Salamanca than to the Monarchomachs to whom those arguments were inaccessible for obvious ideological reasons. The School of Salamanca, not unlike the near contemporary emergence of the ‘liberties of the Gallican Church’, framed royal and papal supremacy within theological parameters that were evoked to defend the sovereignty of the Spanish Cortès. These arguments were known and circulated among the French Catholic theologians who reinterpreted them in the light of the French Wars of Religion even before the League, although they gained special significance for the Holy Catholic League's ‘resistance theory’. Zwierlein demonstrates that the League did not seek to justify the assassination of Henri iii as an afterthought, as these texts were sent in manuscript form to Rome before the event and before being circulated in print form. But beyond the immediate context of the regicide The political thought of the French League and Rome shows that there existed Catholic arguments for the removal of a tyrant that owed nothing to Protestantism. This tradition survived into the seventeenth century and, notably, re-emerged among English Catholics in exile who called for the deposition of James vi & i. The full extent of the intellectual legacy of a Catholic ‘theory of resistance’, distinct from the Protestant one, for the elaboration of modern theories of sovereignty remains to be established. But its lineaments have been painstakingly and authoritatively established here, in an essential book for intellectual historians of the sixteenth century.