The focus of this article is on whether Hillyard's contagion thesis is valid by conducting a preliminary analysis of the Northern Ireland conflict's impact on policing in Britain and the Republic of Ireland. One theme of this analysis is that despite political pressures to draw on any relevant lessons from Northern Ireland, the scale of the conflict and the controversies surrounding policing in Northern Ireland generated counterpressures that prevented the unimpeded transfer of repressive policies, technologies, and practices to policing in Britain and the Republic of Ireland. A second theme is that selected policy development did emerge from the repressive model used in Northern Ireland in terms of emergency legislation and greater police powers. The forging of limits on these developments, however, is still underway in both countries. The transfer process of policies and practices from Northern Ireland to Britain and the Irish Republic has been filtered and reformed under political debate and the differing situations perceived by the public. Scandals surrounding the use and abuse of police powers in the case of the Birmingham Six in Britain and allegations associated with the "Heavy Gang" in the Irish Republic are evidence that toleration of repressive police practices is limited. Further research is necessary to determine the transferable lessons of Northern Ireland regarding police accountability, training, and community relations under circumstances of extreme violence, conflict, and disorder that pose severe threats to public safety. 79 references