The separation of powers doctrine incorporated into the US Constitution includes the ability to declare and enter war. Article I, Section 8 of the Constitution gives Congress the ability to declare war. Article II, Section 2 grants power of the US armed forces to the President as Commander-in-Chief.
Providing a single person with the ability to go to war was an issue of grave concern for the participants of the Constitutional Convention of 1787. Analysis of both the Federalist Papers and the debate record at the Convention verify [PDF] that the framers' chose the words of the Constitution with specificity, expecting each branch of government to retain unique powers regarding military action. Early conflicts tested [PDF] the willingness of a president to expand war power capabilities. President Washington understood that the powers authorizing an offensive operation lay in the hands of Congress and only personally approved defensive maneuvers against Native Americans. Washington also approved defensive military action against agitators during the Whiskey Rebellion, as civil unrest moved beyond mere unhappiness to shootouts and property destruction between 1791 and 1794.
During the Napoleonic Wars, the US passed trade embargoes to circumvent hostile actions by Great Britain and France. Later, the US requested that each country honor neutral trade, but Great Britain continued to thwart commerce and impress US sailors. On June 1, 1812, President Madison implored Congress to issue its first formal declaration of war. The House of Representatives passed the declaration on June 4 and the Senate passed it on June 17, 1812. Madison signed it on June 18, 1812.
The Kennedy, Johnson and Nixon administrations pushed the boundaries of executive power under war powers through the Vietnam War, and Congress responded by passing the War Powers Resolution in 1973. It required the President to tell Congress within 24 hours whenever troops were pledged, and forced the President to remove all troops should Congress not grant an extension within 60 days.
According to a report [PDF] prepared by the Congressional Research Service in January 2007, the Bush Administration drafted a joint resolution post-September 11, 2001 that would have "...authorized the President, without durational limitation, and at his sole discretion, to take military action against any nation, terrorist group or individuals in the world without having to seek further authority from Congress." Congress declined the resolution as presented, but worked quickly to draft a more amenable version. The Authorization for Use of Military Force passed the US House of Representatives and the US Senate on September 14, 2001 and signed [PDF] into law by US President Bush on September 18, 2001. This resolution limited force to actors responsible for the 9/11 attacks and required the President to act within the powers authorized by the War Powers Resolution.
The US Constitution granted separate war powers to both Congress and the President, and neither branch has refrained [PDF] from exercising those powers. During the 19th century, Congress formally declared three wars and authorized the president to engage in military actions on several occasions. In July 1798, President John Adams received approval from Congress to enter the Quasi-War with France and capture French warships. In February 1802, Congress authorized Thomas Jefferson to use military force against Tripoli in the Barbary War. Congress formally declared war for the first time against Great Britain in June 1812. The next formal declaration of war occurred in May 1846, when Congress declared war on Mexico. Congress declared war once more during the 19th century, against Spain in April 1898.
The 20th century saw the formal declaration of war fall to the wayside. The US entered World War I in 1917 after Congress formally declared war against Germany that April, and then against Austria-Hungary that December. World War II was the last war formally declared by Congress, with declarations issued against Japan on December 8, 1941, Germany and Italy on December 11, 1941 and Bulgaria, Romania and Hungary in June 1942. President Franklin Roosevelt interned American citizens of Japanese descent during World War II, and the US Supreme Court held the internment lawful in 1944. In June 1950, the US entered the Korean War upon the orders of President Harry Truman. Truman attempted to use his emergency powers in 1952 to seize production of steel facilities, but the Supreme Court held that the seizure was unconstitutional.
The Vietnam War marked a turning point for the President's war powers.
In August 1964, Congress passed the Gulf of Tonkin Resolution and authorized President Lyndon Johnson to take military action in Southeast Asia. In response to concerns about war powers and the unpopular Vietnam War, Congress legislated the War Powers Resolution in 1971 to regulate executive war powers.
The passage of the War Powers Resolution did not prevent presidents from exercising their war powers. President Gerald Ford evacuated American personnel from Vietnam in April 1975. Jimmy Carter attempted to rescue Americans using US personnel during the Iran Hostage crisis in 1980. Ronald Reagan launched the 1983 invasion of Grenada. George Bush Sr. received approval from Congress to launch the First Gulf War in 1991. William Clinton oversaw several military actions, such as deploying warships to enforce an embargo against Haiti in 1993.
Following the 9/11 terrorist attacks, President George W. Bush launched the invasion of Afghanistan in October 2001. Bush later commenced the invasion of Iraq, the Second Gulf War, in March 2003. The presidential use of military force abroad has continued into the administration of President Barack Obama. In March 2011, Obama lent US air support to operations in Libya and that May ordered the attack that killed Osama bin Laden. In August and September 2013 President Obama contemplated overt military action to intervene in the ongoing Syrian conflict. The question of congressional war power approval surfaced once again. Senator Obama was a critic of presidential use of War Powers Act when the military action was not to stop an imminent or direct threat to the United States. Overt military action in Syria never came to fruition and the debate over the War Powers Act persists.
The War Powers Clause is found in Article I, Section 8, Clause 11 of the US Constitution. It reads, "The Congress shall have Power... To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water." Article II, Section 3 explicitly names the President as the Commander in Chief of the armed forces. However, the power to raise and support the armed forces is reserved for Congress under Article I, Section 7, Clauses 12-16.
During the debate over the content of the US Constitution, convention delegate James Madison proposed that the original terminology "make War" be changed to "declare War" with the goal of ensuring the President maintains the power to dispel acts of aggression. The delegates ratified the change. The role of the President in Article II, coupled with the intentionally ambiguous terminology of the War Powers Clause, has led to an on-going controversy over the proper process for initiating an international conflict under the US Constitution.
Congress has formally declared war five times, with each of these came following a request for such a declaration from the president. Several other military attacks administered by the president have operated under the approval of Congress, including the recent wars in Afghanistan and Iraq. These wars started without Congressional declarations, but received approval after the President petitioned for it under the requirements of the War Powers Act of 1973. The Vietnam War was initiated and conducted under three separate presidents before Congress passed this Act in an effort to force the Executive Branch to seek permission from and involve the Legislature in on-going conflicts.
There have been legal challenges to conflicts initiated without Congressional declaration. In 2003, a lawsuit was filed against President George W. Bush and Secretary of Defense Donald Rumsfeld. The lawsuit, filed by members of the military and their families, alleged that Bush and Rumsfeld did not have the power to initiate a war against Iraq. This lawsuit was dismissed by the courts for being premature, due to there being no set proof that an actual war had been initiated. The Center for Constitutional Rights, with several members of Congress, filed a similar lawsuit against President George H.W. Bush in 1990, by alleging that he did not have the power to declare war against Iraq. This lawsuit was dismissed for similar reasons.
Most recently, several members of Congress filed a lawsuit in 2011 against President Barack Obama for allegedly declaring war against Libya without Congressional approval. This lawsuit was thrown out for failure to prove that there was not a legislative remedy, in light of Congress' power to end the conflict by vote.
10/20/2011: Federal court dismissed lawsuit over US Libya involvement.
06/24/2011: Speaker Boehner sent Obama a letter warning near violating of the 60-day provision of the War Powers Act.
06/16/2011: Obama released report defending military operations in Libya.
06/15/2011: A group of congressmen filed suit against Obama, alleging violation of Article 1, Section 8.
06/15/2011: Obama released report justifying actions and cost in Libya.
07/08/2008: US group co-chaired by Secretaries of State called for report limiting presidential war powers.
03/21/2003: President Bush submitted War Powers notice to Congress.
03/13/2003: First Circuit rejected War Powers appeal.
09/29/1983: Congress invoked War Powers Act for the first time.
11/07/1973: Congress passed War Powers Act....[more]