Environmental regulators often have imperfect information about regulated firms' abatement costs. In this paper we compare taxes and emissions permits in a dynamic setting in which firms behave strategically. The regulator updates policy over time based upon previous aggregate industry...

We analyze a model of environmental regulation with learning about environmental damages and endogenous choice of emissions abatement technology by a polluting firm. We compare environmental policy under discretion, in which policy is updated upon learning new information, versus under rules, in...