What role did the Iroquois Confederacy play in the writing of the constitution?

None whatsoever. There were certain vague cosmetic similarities between the structure of the Iroqois Confederacy and the Constitution which has caused some people with certainpolitical agendas to claim that the one must have been based on the other. We have reasonably good record of the thoughts and debates of the founders however and, while they were highly knowlegeable about Greek, Roman, and English history and made much use of these historical models, they were quite ignorant of the Iroqois.

Answer

One of the main drafters of the American Constitution, Ben Franklin-- did in fact have extensive knowledge about the Iroquios Constitution. As the owner of the print shop where a draft of the Iroquios Consitiution was printed, he had the opportunity to become very familiar with the document. In addition, his urgings to create an American Constitution were in part based on his impression of the Iroquois Constitution that he was already familiar with before America's Constitution was even written.