Pamela Eyring, the president of The Protocol School of Washington, said that while there's no "hard-and-fast" rule, a bow is not appropriate when national leaders meet.
"They're peers. ... Unfortunately, it isn't correct for a chief of state to bow to another chief of state,"
"It's not appropriate. He should not be bowing to other chiefs of state."
She said Obama was clearly trying to show respect, but that the royal couple would not expect such a gesture from a Western leader. Eyring, who reviewed the video of the encounter, said they seemed a "bit uncomfortable" watching Obama bow.
"When you're representing the United States of America, everything speaks ... on behalf of our country," Eyring said. "It's a visual. It shows more of a subservient look."