"Prices versus quantities" (Weitzman 1974), a hugely influential paper, is widely cited (and taught) in current debates about the best policy to reduce greenhouse gas emissions. The paper's criterion for ranking policies suggests that technological uncertainty favors taxes over cap and trade....

Emission allowances are often distributed for free in an early phase of a cap-and-trade scheme (grandfathering) to reduce adverse effects on the profitability of firms. If the grandfathering scheme is phased out over time, firms may nevertheless relocate to countries with a lower carbon price...

Cap and trade mechanisms enjoy increasing importance in environmental legislation worldwide. The most prominent example is probably given by the European Union Emission Trading System (EU ETS) designed to limit emissions of greenhouse gases, several other countries already have or are planning...