United States | United Kingdom | Republican Party (United States) | Democratic Party (United States) | United States House of Representatives | President of the United States | United Nations | United States Senate | United States Navy | United States Army | Supreme Court of the United States | United States Air Force | Native Americans in the United States | United States Congress | Parliament of the United Kingdom | 66th United States Congress | Prime Minister of the United Kingdom | 74th United States Congress | 18th United States Congress | 73rd United States Congress | 54th United States Congress | 61st United States Congress | Senate | United States Marine Corps | United States Department of Defense | 64th United States Congress | 65th United States Congress | 53rd United States Congress | 52nd United States Congress | 55th United States Congress |
Horner has testified before the U.S. Senate Committee on Foreign Relations and the Senate Committee on Environment and Public Works, and works on a legal and policy level with numerous think tanks and policy organizations throughout the world.