If... a society adopts a constitution and incorporates in that constitution safeguards of individual liberty, these safeguards do indeed take on a general moral rightness or goodness. They assume a general social acceptance neither because of any intrinsic worth nor because of any unique origins in someone's idea of natural justice but instead simply because they have been incorporated in a constitution by the people.

The Notion of a Living Constitution.

The Claremont Institute - Bush's Lincolnian Challenge