"The Magna Carta is widely known to be one of the foundational documents for our Constitution. I can only imagine that a mention of that in a court decision would be forbidden by our friends on the right"

John Conyers is referring to the Magna Carta, a file that was checked in 1215 and is widely known to be among the foundational files for our Constitution. He is indicating that the conservative members of the court would not permit a reference of the Magna Carta in a court decision. This is due to the fact that the Magna Carta is viewed as a document that promotes individual rights and liberties, which is something that the conservative members of the court might not concur with. By discussing the Magna Carta, Conyers is recommending that the conservative members of the court are not open to the concept of individual rights and liberties. He is indicating that they would rather stay with the standard analysis of the Constitution and rule out the implications of the Magna Carta.