This book examined whether there is sufficient authority for interstate law enforcement mutual aid to respond to a Mumbai-style attack occurring in the United States. Several existing interstate mutual aid systems were examined to determine if they could be enacted on short notice and provide adequate authority and protections for the responding officers in a no-notice event. This book found that the existing systems for natural disasters and planned events were slow to implement and would not provide the authority and protections required for response to a no-notice event. Our conclusion is that the law enforcement community should create a new national compact that will facilitate the quick response of law enforcement across state lines when required for a notice or no-notice event.