The 13th amendmentSubmitted by Rewind on Wed, 01/23/2008 - 16:58
"If any citizen of the United States shall accept, claim, receive, or retain any title of nobility or honour, or shall without the consent of Congress, accept and retain any present, pension, office, or emolument of any kind whatever, from any emperor, king, prince, or foreign power, such person shall cease to be a citizen of the United States, and shall be incapable of holding any office of trust or profit under them, or either of them."
Rudy Giuliani was just "knighted". This amendment excludes him from holding the presidency. It may well bar any lawyer from seeking office. It was apparently ratified ... and printed in many versions of the US Constitution throughout the 19th century, then it dissapeared.