How parliaments and legislatures participate in war-making has raised interest among researchers from different disciplines, including constitutional law and political science. While war powers are usually considered to be included in the field of the executive branch, parliaments have played an increasingly relevant role as more democratic decision-making in both normal and exceptional times has gained prominence. The comparative aspect to examine war powers between parliaments or between the branches of government is often adopted to describe the authority and legitimacy of these powers. The US Congress is considered to have strong war powers on paper compared to parliaments in other liberal democracies. Many times, the experienced realities of war have, however, resulted in benefiting the executive branch. This article claims that Congress, however, has not given away its powers but has adapted them to the changing conditions. The debates on authorizations of use of force can be seen as momentum for Congress to address its constitutional war powers. This article draws on congressional debates on war powers with regard to authorization of using US armed forces against Iraq in 2002. The purpose is to show a vivid discussion on struggles concerning constitutional war powers and how these are interpreted, defined and understood against the background of historical, theoretical and constitutional discussions on war powers. As the committing of US armed forces and the separation of powers continue to be in the center of political discussions, it is relevant to examine the debates on war powers in the US Congress.