When the framers drafted and debated the Constitution, the powers over war and spending were considered essential to legislative prerogatives and republican government. Much of the war power has drifted to the president, especially after World War II. Beginning with Harry Truman's war against North Korea in 1950, presidents have repeatedly insisted that they may obtain authority to use military force not from Congress but from the UN Security Council and the North Atlantic Treaty Organization (NATO) (Fisher 1997). The most recent example of this exercise of presidential power is the military operation by President Barack Obama in Libya in 2011 (Fisher 2012). Unilateral presidential decisions to commit U.S. troops to hostilities result in financial obligations that must be paid by Congress, even if it had no role in the commitment.
Power of the Purse
In Federalist No. 58, James Madison called the power of the purse "the most complete and effectual weapon with which any constitution can arm the immediate representatives of the people, for obtaining a redress of every grievance, and for carrying into effect every just and salutary measure" (Wright 2002, 391). He understood the essential tie between this power and republican government. In that same essay he explained the evolution of the spending power in the British Constitution: "an infant and humble representation of the people gradually enlarging the sphere of its activity and importance, and finally reducing, as far as it seems to have wished, all the overgrown prerogatives of the other branches of the government."
After a centuries-long struggle, the British Parliament used the power of the purse to gradually place limits on the monarch. English kings tried to circumvent Parliament by reaching to outside sources to finance military expeditions and other initiatives. Some of those funds came from private parties and foreign governments. Fueled by those transgressions, England lurched into a bloody civil war, and Charles I lost both his office and his head (Einzig 1959, 57-62, 100-06). With Iran-Contra, President Ronald Reagan also decided to pursue executive policies by relying on private and foreign money. As explained later in this article, he managed to escape impeachment.
Madison spoke plainly in Federalist No. 58: "the legislative department alone has access to the pockets of the people" (Wright 2002, 345). Language in Article I, section 9, of the U.S. Constitution reflects that principle: "No Money shall be drawn from the Treasury, but in Consequence of Appropriations made by Law." Other provisions in Article I underscore legislative control over the purse. Congress is empowered to lay and collect taxes, duties, imposts, and excises; borrow money on the credit of the United States; and to coin money and regulate its value. Madison argued against placing the power of commander in chief in the same hands as the power to go to war: "Those who are to conduct a war cannot in the nature of things, be proper or safe judges, whether a war ought to be commenced, continued, or concluded. They are barred from the latter functions by a great principle in free government, analogous to that which separates the sword from the purse, or the power of executing from the power of enacting laws" (Hunt 1906, 6:148, emphasis in original).
Notwithstanding the clarity of Article I, section 9, presidents have attempted to wrest the spending power from Congress by entering into financial obligations not authorized by law. An example is President Thomas Jefferson and the Louisiana Purchase, but he understood that his initiative required the approval of Congress for additional funds and Senate consent to a treaty (Sofaer 1976, 185-86, 196-98). Other presidential actions pose much graver threats to constitutional government, such as initiating wars, refusing to spend money that Congress appropriates, and seeking funds from foreign governments and private citizens in violation of statutory policy, as with Iran-Contra. …