Pigouvian taxes can fully correct for market failures due to externalities, but actual policies are commonly forced to deviate from the Pigouvian ideal due to administrative or political constraints. This paper derives sufficient statistics, which require a minimum of market information, that...

Firms sometimes comply with externality-correcting policies by gaming the measure that determines policy. We show theoretically that such gaming can benefit consumers, even when it induces them to make mistakes, because gaming leads to lower prices by reducing costs. We use our insights to...