By Bill Mears, CNN Supreme Court Producer
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Washington (CNN) - At his request, President Barack Obama is ending his inaugural oath with: "So help me God."
Those four words are not legally or constitutionally required, unlike other federal oaths that invoke them as standard procedure.
Historians have wrangled over whether George Washington established precedent by adding the phrase on his own during his first Inaugural acceptance, but the Library of Congress website states he did.
