Massachusetts et al. v Environmental Protection Agency: implications for public health policy and practice.

This installment of reviews the U.S. Supreme Court's April 2, 2007, decision in and considers its implications for public health policy and practice. This landmark decision focused on a central concern in administrative law; namely, when an agency vested with the authority to regulate in the public's health has the power to refuse to carry out a legislative directive. The subject of the case was regulation of greenhouse gas emissions by new motor vehicles under the section 202(a)(1) of the Clean Air Act, but the central question was allocation of powers between a legislative branch that desires action and an executive branch agency that for policy reasons refuses to act.