Americans today may take the Bill of Rights for granted, but its inclusion in the U.S. Constitution originally was controversial. To understand why, I turn to James Wilson, a leading statesman of the founding era and the chief opponent of the Bill of Rights. Among other things, Wilson thought a bill of rights would bind future generations to an incomplete list of rights and deprive them of the right to define individual rights over time. His arguments against a constitutional bill of rights also offer a useful view of the complexity and diversity of American founding era thought.