A federal judge ruled Friday that a lobbyist and former Environmental Protection Agency (EPA) official can testify for a coal company in its lawsuit against the agency. The EPA had sought to block Jeff Holmstead, who led the EPA’s air pollution office under then-President George W. Bush from 2001 to 2005, from appearing as an expert witness in Murray Energy Corp.’s case. The agency argued that Holmstead’s time at the EPA is a significant conflict of interest and his testimony would amount to little more than unreliable legal conclusions. The EPA “effectively argues that, because Mr. Holmstead once worked at...