Make a direct reference to the U.S. Constitution by using phrases such as, "According to the U.S. Constitution ..." or "Referring to the U.S. constitution ..."
Embed the citation to the end of the sentence in parenthesis. For every citation, begin with "U.S. Const." followed by the article number, amendment, section and clause numbers in that order. Article should be abbreviated as "art," clause as "cl.," section as "sect." and amendment as "amend."
Cite the constitution in a reference list. Follow the same format as outlined in Step 2 and add additional decisions made by the court followed by the year the decision was made. For example, if the U.S. Constitution repealed the 1993 decision for amendment 18, your reference list would include:
U.S. Const. amend. XVIII (repealed 1933)