The Vietnam War is perhaps the best illustration of the tension that can develop between executive and legislative powers, specifically when Congress does not support a war effort. Although the conflict in Vietnam was definitely a war in terms of its effects on the lives of Americans and Vietnamese, Congress never declared it one. The conflict in Vietnam was technically considered a "police action" by constitutional standards.

Use the slides below to explore how the ambiguity of the Constitution about a president's war powers resulted in a U.S. military involvement that Congress--and most of the American public--did not really want. Click the audio button beneath each image to hear about the stages of the United States' entry into the Vietnam War.

During the Vietnam War, with many in Congress suspicious of the evidence presented by President Johnson and his secretary of defense, the relationship between the executive and legislative branches essentially fell apart. Meanwhile, the Supreme Court was unable to interfere with Johnson's executive order initiating U.S. involvement in Vietnam since his actions appeared at least somewhat in line with the constitutional authority granted to the president.

By 1973, Congress was no longer trying to withhold its support from military operations in Southeast Asia. The War Powers Resolution was passed that year allowed the executive branch to direct the Vietnam War effort without consultation with Congress. Both Nixon and the Vietnam War are now subjects of much skeptical historical research, but the War Powers Resolution has nonetheless remained in effect for more than 40 years. As was demonstrated during the Vietnam era, Congress can only interfere with an executive order during wartime by passing a law that orders a troop withdrawal. According to the Constitution's systems of checks and balances, however, such a law would still be subject to a presidential veto. If the president is able to find 34 senators to support the veto, then he or she is able to continue with the war effort--even if the other 501 members of Congress are against it.