[JURIST] US Supreme Court Chief Justice John Roberts [official profile] on Thursday allowed the Environmental Protection Agency (EPA) [official website] to continue enforcing [SCOTUSblog report] of its rule aimed at suppressing air pollution caused by mercury as well as other toxins from power plants. Roberts denied a petition [text, PDF] filed [JURIST report] by Michigan and 19 other states last week seeking to block enforcement the Mercury and Air Toxics Standards (MATS) [materials, PDF] pending a petition for certiorari. MATS, which requires installation of technology in electricity-generating power plants to curb air pollution caused by mercury and other harmful materials, was promulgated pursuant to the EPA interpretation of a portion of the Clean Air Act (CAA) [materials, PDF]. The states argued that the EPA went beyond “the bounds of reasonable [statutory] interpretation” in reading the CAA to allow the agency to “ignore cost when deciding to regulate power plants.” Roberts denied the petition unilaterally [The Hill report] without referring the matter to the other justices.

Last month the Supreme Court ordered that the Obama administration delay enforcement [JURIST report] of the EPA’s Clean Power Plan (CPP) [materials] pending a resolution to legal challenges. The request to block the implementation of the CPP was made in late January, with states insisting [JURIST report] that the plan’s implementation would create a burden on states. Regulating power plan emissions has been a contentious issue. In June the Supreme Court ruled [JURIST report] 5-4 that the EPA could not make regulations regarding the toxic emissions of power plants without considering costs.