This new edition continues to serve as a core textbook covering the fundamental history, formation, oversight, and reach of the current Department of Homeland Security as it has changed and developed over the last ten years. The text is fully updated with new laws, regulations, and strategies across intelligence, transportation sectors, emergency management, border security, public utilities, and public health. The author provides an objective, balanced perspective on the priorities and challenges federal and state government agencies are faced with in the areas of counterterrorism, emergency management, and protecting critical infrastructure.