In the two years since they started a debate club, the prisoners have beaten teams from the US Military Academy at West Point and the University of Vermont. The competition with West Point, which is now an annual affair, has grown into a rivalry.

At Bard, those who help teach the inmates aren't particularly surprised by their success.

"Students in the prison are held to the exact same standards, levels of rigour and expectation as students on Bard's main campus," said Max Kenner, executive director of the Bard Prison Initiative, which operates in six New York prisons. "Those students are serious. They are not condescended to by their faculty."

Students on the Harvard team weren't immediately available for comment, but shortly after the loss they posted a comment on a team Facebook page.

"There are few teams we are prouder of having lost a debate to than the phenomenally intelligent and articulate team we faced this weekend," they wrote. "And we are incredibly thankful to Bard and the Eastern New York Correctional Facility for the work they do and for organising this event."