The standards were adopted in 2012 and were to have taken effect this year, requiring coal or oil-burning plants to drastically reduce their mercury emissionsThe US Supreme Court on Monday rejected federal environmental regulations requiring power plants to limit emissions of mercury and other pollutants, in a defeat for the Obama administration. In a 5-4 decision split along conservative and liberal lines, America’s top court sided with 23 states and industry groups who had protested the cost of standards imposed in 2012 by the national Environmental Protection Agency (EPA).