"In modern nations, political disagreement is the source of both the gravest danger and the greatest security," writes Cass Sunstein. All democracies face intense political conflict. But is this conflict necessarily something to fear? In this provocative book, one of our leading political and legal theorists reveals how a nation's divisions of conviction and belief can be used to safeguard democracy.

Confronting one explosive political issue after another, from presidential impeachment to the limits of religious liberty, from discrimination against women and gays to the...