Law often allocates risk, as through tort doctrines. Should people be able to undo or "reverse" such risk allocations by, for example, selling their rights to any claims that may later develop? Scholars have interestingly examined this question, as well as many other innovative ideas for rearranging risk outside of traditional insurance markets. This talk focuses attention on some related but underexplored questions surrounding risk reversibility itself—such as the optimal amount of stickiness in society's default risk allocations, the effects of heterogeneity in risk arrangements, and the implications (cognitive and otherwise) of starting from one risk baseline rather than another. Lee Fennell is Professor of Law at the University of Chicago Law School. This talk was recorded October 22, 2008, as part of the Chicago's Best Ideas series. Chicago’s Best Ideas, a lecture series begun in honor of the University of Chicago Law School’s Centennial, highlights the intellectual innovations of the School’s distinguished faculty.