  Civil liability for a lost chance applies to legal cases in which a tortious
action changes the probabilities of the outcomes that can be obtained by the
victim. A central point in the application of this type of liability is the
valuation of damages. Despite the practical importance of the valuation of lost
chances, the legal restrictions that guide it have rarely been discussed
explicitly. In order to discuss these restrictions, we propose an abstract
description of a lost chance case in which there are multiple possible outcomes
and the victim can make a choice that affects these outcomes. Given this
description, we propose six conceptual questions to guide the valuation of lost
chances. We discuss alternative answers to these questions and present the
formulas that derive from them. More specifically, we show that the main
formulas that have been proposed for medical misdiagnosis cases are particular
instances of the alternatives we discuss.
