Many governments and businesses would like to minimize or eliminate the greenhouse gases that result from their purchases of power from electricity grids. Because electricity flows cannot be traced from purchasers back to specific generators, some regulators and users have proposed an...

For political, jurisdictional and technical reasons, environmental regulation of industrial pollution is often incomplete: regulations apply to only a subset of facilities contributing to a pollution problem. Policymakers are increasingly concerned about the emissions leakage that may occur if...