The Ninth Amendment may seem a strange subject for a lecture at a conference on the recent decisions of the Supreme Court. After all, the Court has never squarely based a holding on the Ninth Amendment and has scarcely even discussed its meaning. Some scholars regard the amendment as an ‘‘inkblot’’ or as nothing more than a warning not to read the enumeration of powers too liberally or the enumerated rights too narrowly. It plays virtually no role in modern constitutional litigation. And yet the Ninth Amendment is the subject of two recent books and many articles, and rightly so: the amendment, properly understood in light of its text and history, helps us understand the constitutional structure of powers granted and rights reserved, the relation of the Bill of Rights to the original Constitution of 1787, and the role of natural rights in American constitutionalism.