Mr. Sansonetti leads Holland & Hart's Natural Resources Department, which is ranked as the best natural resources practice in the country by Best Lawyers in America.

Mr. Sansonetti served as the Assistant Attorney General for the Environment and Natural Resources Division (ENRD) of the Department of Justice from December 2001-April 2005. As one of the top leaders in the Justice Department, he was deeply involved in responding to post-9/11 events, including working with the new Department of Homeland Security. He managed a budget of $115 million and supervised 650 employees including a legal staff of 425 attorneys. Mr. Sansonetti rejoined Holland & Hart's Cheyenne, Wyoming office on May 1, 2005.

Mr. Sansonetti is a recognized expert in air quality, geothermal development, water rights, water quality, the Endangered Species Act, surface mining, Indian law, natural resource damage assessments, takings, public lands management, Superfund, and many other areas of natural resources law. He has argued before the U.S. Supreme Court and in the Federal Circuit Courts of Appeal, and served as a federal prosecutor in environmental crimes cases.

Mr. Sansonetti joined Holland & Hart in 1993, where he developed a national practice in natural resources and environmental law. From 1990 to 1993, Mr. Sansonetti was Solicitor of the Department of the Interior, the number three ranking position in DOI. During his tenure, he signed the $1.1B Exxon Valdez oil spill settlement, having served as one of the six federal negotiators, and was Counsel to the Endangered Species Committee for the Spotted Owl hearings in Oregon.

Active in politics, Mr. Sansonetti was the Administrative Assistant and Legislative Director for Wyoming Congressman Craig Thomas during the 101st Congress and was appointed Associate Solicitor for Energy and Resources by Interior Secretary Don Hodel during the last two years of the Reagan administration. He also served as Wyoming's Republican National Committeeman (1996-2001) and as General Counsel for the Republican National Committee (2001). He was the chairman of the Republican Party in Wyoming from 1983-1987.

Mr. Sansonetti has been listed in Best Lawyers in America since 2007 for Environmental Law and Government Relations Law.