preamble:

WE the PEOPLE in order to form a more perfect union, establish justice, insure domestic tranquility, provide for the common defense, promote the general welfare, and secure the blessings of liberty to ourselves and our posterity, do ordain and establish this CONSTITUTION for the UNITED STATES OF AMERICA

Article I: LEGISLATIVE DEPARTMENT

  Section VIII:  Powers granted to congress:

                       Part 3:  It may regulate foreign and interstate trade:  To regulate commerce with foreign nations, and among the several states, and with the Indian tribes.

AMENDMENT IX:  Concerning rights not enumerated:

                     The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.