Jon Elster's Ulysses Unbound: Studies in Rationality, Precommitment, and Constraints takes a hard-nosed approach to the question of why governments would agree to commit themselves under a constitution. His analogy of Ulysses bound while passing the sirens is extremely helpful. The book is filled with both theoretical insights and discussions of cases from not only the U.S., but also Europe. Not only does it discuss the usual reasons for precommitment (e.g., tempering passions, efficiency), but it also explores their relationship with commitment mechanisms (e.g., delay, supermajority). No wonder this has become a classic in the comparative constitutions field.