The Constitution is the supreme law of a nation or state, and it provides for its internal operations. In some states (but not all) the constitution has supremacy over ordinary statutory law, and is often referred to simply as “the law”. It is also considered to be the “source of authority” for government officials. For example, if an official acts in a way that is expressly prohibited by the Constitution, the act may be nullified.
The Congress shall have Power to make all Laws necessary and proper for carrying into Execution the foregoing Powers, and for the Purposes of regulating Commerce among the several States, and with Foreign Nations; to establish Post Offices, and to post and maintain a Navy; to raise Money for the Support of the Common Defence, and for the Payment of the Militia when called into Active Service; to declare War, and provide for the Punishment thereof; and for other Purposes as Congress may think proper.
The judicial Power of the United States shall be vested in one Supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish. The judges of the Supreme and inferior Courts shall hold their Offices during good Behaviour, and receive for their Services a Compensation which shall not be diminished during their Continuance in Office.