 Revelations of government surveillance on private citizens in the aftermath of the 9-11 attacks have shocked and worried Americans across the country. The increase in domestic government surveillance after 9-11 was possible because of the systems and practices set in place long before the attacks. Domestic surveillance tactics were first designed to facilitate foreign interventions and then brought home. We call this the boomerang effect. Interventions that were first aimed abroad return home and are used to monitor citizens. Preparing for and engaging in foreign interventions provides a testing ground for intervening governments to experiment with new forms of social control. These methods of control often return home. The result is that the intervening government becomes more effective at not only controlling foreign populations but domestic populations as well. The groundwork for the modern surveillance state can be traced back to one man, Captain Ralph Van Diemen. His story illustrates the boomerang effect. In 1901, Captain Ralph Van Diemen took command of the Division of Military Information in the Philippines. Using state-of-the-art technology and organizational techniques, the Division collected data on Filipino citizens in order to suppress dissent to the U.S. occupation following the Spanish-American War. After returning to the United States, Van Diemen began meeting with military leaders to convince them to create a dedicated domestic intelligence agency. He was ultimately successful and in 1917, the military intelligence section was formed with Van Diemen at the helm. Under Van Diemen's leadership, it was renamed the Military Intelligence Division and restructured into 12 subdivisions. The surveillance state grew quickly. The Codes and Ciphers Division, MI-8, secretly reviewed communications passed over American cables. The Foreign Influence Division partnered with the American Protective League, an organization of private citizens, to identify anti-war advocates, radicals, and German sympathizers within the United States. In just over a year, the partnership yielded over 1 million pages of surveillance on German-Americans and conducted over 3 million investigations for the government. These activities resulted in a nationwide surveillance network. When this network became public knowledge, there was widespread criticism. In 1929, Secretary of State Henry Stimpson closed MI-8, stating that, Gentlemen do not read each other's mail. However, the foundations of a large-scale, centralized, national surveillance state were firmly entrenched. In 1952, a panel appointed by President Truman produced the Brownell Report. The report detailed the operations and failures of the Armed Forces Security Agency, which was founded in 1949 to achieve efficiency and economy in the government's intelligence services. As part of these reforms, the agency was rebranded as the National Security Agency. Over the next several decades, the NSA, along with the CIA and FBI, pursued covert operations and gathered intelligence on domestic political groups and American citizens. In 1974, Seymour Hirsch published an article in The New York Times exposing the government's surveillance operations against U.S. citizens. In response, the Church Committee revealed the massive scale and scope of intelligence operations and the resulting abuses against liberties of people in the United States. A number of reforms were implemented, including the Foreign Intelligence Surveillance Act of 1978, which attempted to place constraints on the U.S. government's surveillance activities. The weakness of these constraints became evident following the 9-11 attacks, when a series of whistleblowers revealed that the NSA and other government agencies once again significantly increased their collection of information on private individuals. The present use of domestic surveillance in the U.S. is clear evidence of the boomerang effect. Surveillance was first developed in the Philippines and then returned back, like a boomerang, to the U.S. through training, recent technological innovations, and the mindset of monitoring and defeating potential threats. Today, there's unprecedented technological access to and amassing of data, threatening the liberties of American citizens. To learn more about the boomerang effect and its impacts on domestic civil liberties, buy our new book. Tierney Comes Home, The Domestic Fate of U.S. Militarism. To learn more about Hayek program research and graduate student opportunities, visit hayek.marcadis.org.