The basic functions of the United States government are defined in the Preamble to the U. S. Constitution. The Supreme Court is one example of how the U. S. government

The Preamble to the United States Constitution is a brief introductory statement of the Constitution's fundamental purposes and guiding principles. It states in general terms, and courts have referred to it as reliable evidence of the Founding Fathers' intentions regarding the Constitution's meaning and what they hoped the Constitution would achieve.