Where a written constitution provides the foundation for a political regime, the principles of constitutional law for that regime are derived by interpretation of the language of the document; these interpretations are then applied in making governmental decisions and settling constitutional controversies. Some constitutional language is so specific that little interpretation is required, as, for example, the provision that the U.S. president “shall hold his office during the term of four years.” But most constitutional language leaves room for varying views as to its meaning, and such provisions as “due process of law” or “freedom of speech” or “unreasonable searches and seizures” can never be applied without making a choice among alternative interpretations.
Whose responsibility is it to interpret a written constitution and authoritatively to declare constitutional law? An important part of this function falls to the executive branch, which must inevitably and continually interpret the constitution in making decisions on the use of executive power. In 1841 a U.S. president died in office for the first time. The language of the constitution left it unclear whether it was the “office,” or only the “powers and duties” of the office which devolved on the vice-president. This important constitutional question had to be determined by the then vice-president, John Tyler, who, after some initial hesitation, decided that he was actually president and not simply vice-president acting as president. This view was quickly accepted as the constitutional law on presidential succession.
Congress also must continuously construe the constitution as a guide to action. For example, the constitution authorizes the president to make treaties, “by and with the advice and consent of the Senate.” George Washington assumed that this provision meant that he should sit down with the senators and get their advice on treaties while they were being negotiated, but when he went to the Senate for this purpose, the senators preferred not to discuss the matter in his presence and voted to refer it to a committee. Washington had no choice but to withdraw, yielding to the Senate's interpretation of “advice and consent,” and no subsequent president has ever sought to repeat this tactic.
These two instances indicate how it is possible for the executive and the legislature to make binding interpretations of their own respective powers under a constitution. In fact, it was argued by many during the early years of the American republic that each branch of government should be the authoritative interpreter of all those provisions dealing with its own status and powers. However, this tripartite theory of constitutional interpretation was strongly challenged by Justice Marshall in the 1803 case of Marbury v.Madison (1 Cranch 137), where he asserted the primacy of judicial interpretation of the constitution.
In the Marbury case the Supreme Court declined to enforce a statute duly enacted by Congress because, as Marshall interpreted the act, it was contrary to the constitution. The judicial power to declare acts of Congress unconstitutional is not explicitly stated in the constitution, and the argument as to whether the drafters intended the Court to have such power has never been entirely settled. Some of the major battles of American politics have resulted from legislative or executive resistance to the Court's interpretations, and notable efforts have been made to deny the supremacy of judicial views on constitutional interpretation. Both Andrew Jackson in his veto of the Bank Bill in 1832 and Abraham Lincoln in his first inaugural address took this position.
In spite of such opposition, the Supreme Court's qualifications to act as pre-eminent interpreter of the constitution have been generally accepted. The Court has minimized resistance to its role by adopting rules of self-restraint, which keep it from passing on certain constitutional questions of a “political” nature, and has generally been deferential toward the constitutional interpretations by the president and Congress. It has seldom asserted a constitutional position that challenged a dominant popular opinion, although there have been such “self-inflicted wounds” as the Dred Scott decision in 1857 and the invalidation of the income tax in 1895.
During the twentieth century the Court's most serious miscalculations on constitutional issues came in 1935 and 1936, when it declared a number of New Deal statutes unconstitutional. President Roosevelt was unable to get through Congress legislation authorizing him to appoint additional justices who would support the New Deal; but in 1937 the Court itself reversed its position, thus terminating the dispute. Two decades later the Court's constitutional views again became the center of controversy, primarily on the issue of racial segregation in the public schools, but also on certain national security issues in 1957, on legislative apportionment in 1962, and on the problem of religion in the public schools in 1962 and 1963.
The enormous prestige of the United States Supreme Court has helped to popularize judicial review of legislation and judicial supremacy in constitutional interpretation. Prior to World War II it was primarily in federal systems within the British Commonwealth—notably Canada and Australia— that courts with constitutional responsibilities somewhat comparable to the U.S. Supreme Court were found. However, following World War II constitutional courts were established in West Germany, Italy, India, and elsewhere.