William Hubbs Rehnquist was an American lawyer, jurist, and a political figure who served as an Associate Justice on the Supreme Court of the United States and later as the Chief Justice of the United States. Considered a conservative and strict constructionist, Rehnquist favored a federalism under which the states meaningfully exercised governmental power. Under this view of federalism, the Supreme Court of the United States, for the first time since the 1930s, struck down an Act of Congress as exceeding federal power under the Commerce Clause.

Rehnquist presided as Chief Justice for 19 years, making him the fourth-longest-serving Chief Justice after Melville Fuller, Roger Taney and John Marshall, and the longest-serving Chief Justice who had previously served as an Associate Justice. The last 11 years of Rehnquist's term as Chief Justice marked the second-longest tenure of one makeup of the Supreme Court.