Control orders have been a striking part of the anti-terrorism response of the United Kingdom and Australian governments in modern times. They provide a means for the substantial restriction of an individual’s liberty on the basis that doing so will be likely to prevent the occurrence of a terrorist act. While posing a clear challenge to the presumption of innocence, the orders have been just as controversial for practical reasons as well as principle. The utility and effectiveness of these preventive orders have remained uncertain through legal challenges and independent reviews, and those questions persist about the similar Terrorism Prevention and Investigation Measures that replaced control orders in the United Kingdom in 2011. The orders in both countries have not just proved remarkably impervious to statutory repeal, but have in fact continued to expand in scope.