A native of Omaha, Nebraska, Pemberton is a senior vice president and general counsel of operations for Southern Company. Pemberton was formerly Republican chief counsel for the U.S. Senate Environment and Public Works Committee. He then became Chief of Staff to Jeff Holmstead in the Environmental Protection Agency's Office of Air and Radiation of the Environmental Protection Agency from 2001-2003, during the George W. Bush presidency. Pemberton also worked for the Washington Legal Foundation, which is known for its anti-activist position and has received funding from the Claude R. Lambe Foundation, a charitable foundation run by the Koch brothers.
While Pemberton worked for the EPA, the agency effectively repealed the Clean Air Act's "new source review" provision, which requires companies to install modern pollution control technologies in new plants and in old plants when they make modifications that significantly increase pollution. Pemberton, Jeff Holmstead’s chief of staff at the Office of Air and Radiation, was hired by electricity giant Southern Company only one week after the EPA designed the New Source Review loopholes. He joined Southern Company as a lobbyist.
Pemberton has been named a "Top Lobbyist" by The Hill magazine.
Southern Company has spent just under $92 million on lobbying since Pemberton joined in 2003.