"This thesis argues that civilian law enforcement is more effective than military law enforcement against domestic terrorism. It uses a case study approach to analyze government reactions to terrorism in Canada against the FLQ, and in Northern Ireland against the IRA. It concludes that the best approach to domestic terrorism is a combination of civilian and military security forces working together. Within this framework, the military should maintain a support role to the civilian police. As a result, amendment or repeal of the Posse Comitatus Act is unnecessary. As written, the law provides adequate flexibility for government leaders to deploy military troops as the need arises. Furthermore, this thesis provides lessons learned for policymakers considering the deployment of military to combat domestic terrorism."