Contrary to the conventional wisdom among economists and legal scholars, command-and-control (CAC) environmental regulations are not inherently inefficient or invariably less efficient than alternative economic instruments (EI). In fact, CAC regimes can be and have been efficient (producing net social benefits), even more efficient in some cases that alternative EI regimes. Standard economic accounts of CAC are insensitive to the historical, technological, and institutional contexts that can influence (and sometimes determine) the efficiency of alternative regulatory regimes. A regime that is nominally or relatively efficient in one set of circumstances may be nominally or relatively inefficient in another. In some cases, given the margin...