AMERICAN NOTES: Last Carte Blanche

With only two dissenting votes, Congress in August 1964 passed the Tonkin Gulf Resolution, which authorized the President "to take all necessary steps, including the use of armed forces," to protect American units in Southeast Asia from attack and to aid U.S. allies there. It was the closest Congress ever came to making the nation's longest war official, and it gave Lyndon Johnson support in escalating the American involvement in Viet Nam.

As opposition to the war increased, however, many legislators came to regret their original votes. This month, Congress quietly rescinded the Tonkin measure—tucking the provision, ironically, into a...