Spurred by the advances in option theory that have been remaking financial and economic scholarship over the past thirty years, a revolution is taking shape in the way legal scholars conceptualize property and the way it is protected by the law. Ian Ayres's Optional Law explores how option the ory is overthrowing accepted wisdom and producing tangible new tools for courts in deciding cases. Ayres identifies flaws in the current system and shows how option theory can radically expand and improve the ways that lawmakers structure legal entitlements. An option-based system, Ayres shows, gives parties the option to purchase - or the option to sell - the relevant legal entitlement. Choosing to exercise a legal option forces decisionmakers to reveal information about their own valuation of the entitlement. And, as with auctions, entitlements in option-based law naturally flow to those who value them the most. Proposing a practical approach to the ongoing question of how to effectively structure legal entitlements, Optional Law will be applauded by legal scholars and professionals who continue to seek new and better ways of fostering the fairest legal judgments possible.