Optimal environmental border adjustments under the General Agreement on Tariffs and Trade

A country's optimal environmental border policy includes a strategic component that is inconsistent with commitments under the General Agreement on Tariffs and Trade (GATT). We extend the theory to include GATT compliance. Theory supports optimal border adjustments on carbon content that are below the domestic carbon price, because price signals sent through border adjustments encourage consumption of emissions intensive goods in unregulated regions. The theory is supported in our applied numeric simulations. Countries imposing border adjustments at the domestic carbon price will be extracting rents from unregulated regions at the expense of efficient environmental policy and consistency with international trade law.