Chicago 7 (University of Chicago Manual of Style, “Capitalization, Titles”, http://www.chicagomanualofstyle.org/CMS_FAQ/CapitalizationTitles/CapitalizationTitles30.html)
Q. When I refer to the government of the United States in text, should it be U.S. Federal Government or U.S. federal government? A.The government of the United States is not a single official entity. Nor is it when it is referred to as thefederal government or the U.S. government or the U.S. federal government. It’sjust a government, which, like those in all countries, has someofficial bodies that act and operate in the name of government: the Congress, the Senate, the Department of State, etc.