This thesis aims to show the significance the power to define may have. It analyzes the policy process and policy outcomes regarding the status, treatment and form of trial given to the “enemy combatants” during the George W. Bush administration and the War on Terror, and how the Bush administration used its power to define with relative success. The analysis is provided by a close reading of four documents central to the policy process. The four documents are two memoranda from within the executive branch, a presidential signing statement, and an executive order. The policy choices made and the degree the Bush administration used its power to define proved to have significant consequences for the balance of power between the three branches of government, and for the “enemy combatants.” By applying three theories on the policy process, the analyzed documents and their context the thesis attempts to find if the theories may provide additional insight into how George W. Bush ran the executive branch, and why the policy outcomes turned out as they did.In the aftermath of the terrorist attacks on September 11, 2001, Bush declared a “War on Terror” which led to the invasion of two Middle Eastern countries, Afghanistan and Iraq. The two wars led to an influx of prisoners held by the United States’ military and the Central Intelligence Agency, most prominently in the prison facilities at Guantanamo Bay, the Abu Ghraib prison outside Baghdad and in secret CIA-operated prisons in several undisclosed locations around the world. The influx of prisoners and a need to prevent further terrorist attacks on American soil caused the Bush administration to use its defining powers to initiate a host of controversial policies. Leading among these was the policy choice to remove the protections provided the prisoners by the Geneva Conventions and the United States Constitution, the creation of the “enemy combatants,” and a new and very narrow definition of what constituted torture. Congress and the Supreme Court tried to curb the increased powers the executive claimed, and the policy choices the administration made with regard to the enemy combatants. The attempts made by the two other branches of government gained only limited success for the majority of Bush’s two terms, but the Supreme Court was able to strike some of Bush’s policies down in two central cases; Hamdan v. Rumsfeld, and Boumediene v. Bush. After Barack Obama took office he has reversed almost every policy choice the Bush administration made with regard to the enemy combatants, which signals a new course for the executive branch and the United States’ government.