The president has the power to wage war. The president’s role as commander-in-chief provides for civilian control of the military. The U.S. legislature’s power to declare war and the president’s power to command the armed forces are examples of the system of checks and balances. The War Powers Resolution (1973) was an attempt to clarify the relationship between the president and Congress in military matters.
Supreme Court cases involving the president’s power as Commander in Chief include Korematsu v. United States (1944) and Youngstown Company v. Sawyer (1952).
The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States; he may require the Opinion, in writing, of the principal Officer in each of the executive Departments, upon any subject relating to the Duties of their respective Offices, and he shall have Power to Grant Reprieves and Pardons for Offenses against the United States, except in Cases of Impeachment.
He shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur; and he shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States, whose Appointments are not herein otherwise provided for, and which shall be established by Law: but the Congress may by Law vest the Appointment of such inferior Officers, as they think proper, in the President alone, in the Courts of Law, or in the Heads of Departments.