When does the creation of benefits to some people justify the imposition of harms on others?  This is a central question for public policy.  Despite rhetorical claims of win-win solutions, all policies impose harms on some people, at least in the sense of opportunity harms—forgoing an alternative policy that would provide greater benefits to these individuals.  An increasingly common method for answering this question is to use benefit-cost analysis (BCA) to compare the monetary value of the gains to those who benefit to the monetary value of the losses to those who are harmed.  If the aggregate value of the gains exceeds that of the harms, the policy is said to yield positive net benefits relative to the status quo and to constitute an improvement in social welfare.