p. 263 A New Birth of Freedom, Jaffa

In what regard can we say that "legislating morality" is the only way to secure the consent of the governed?

...Certainly the laws governing marriage and the family were as "domestic" as those concerning master and servant. The first platform of the Republican Party, in 1856, denounced the 'twin relics of barbarism, polygamy and slavery.' Jefferson, in his Bill for Proportioning Crimes and Punishment for Virginia in 1779, grouped, 'rape, sodomy, and bigamy' as felonies of equal heinousness. During the Lincoln-Douglas debates, Lincoln trapped Douglas with the inconsistency of his doctrine of popular sovereignty which presumably left the people of a territory or a state 'perfectly free' to decide for themselves what their domestic institutions would be. Yet Douglas would not accept Utah either as a territory or state unless polygamy was abolished.

It was clear to Lincoln, although not so clear to many of his contemporaries, that the 'consent of the governed' could be rightfully exercised only within the boundaries of a moral law that gives consent its validity but whose validity does not depend upon consent.