(CBS News) NEW YORK - Presidential debates are run by a commission that operates independently of the political parties.
The campaigns have no say in the choice of the moderator and at every debate there's no telling what might happen -- any mistake or zinger could be a game changer in the election. Just look at some memorable moments in past elections.
The first televised debate aired in 1960 and politics would never be the same. That night the young Senator John Kennedy was cool and collected. The experienced Vice President Richard Nixon looked uncomfortable, even sweaty.
The first lesson: The debates would not just be about what you said, but how you looked when you said it.
And mistakes could have huge consequences. In 1976, at the height of the Cold War, President Gerald Ford mysteriously declared, "There is no Soviet domination of Eastern Europe."
He lost to Jimmy Carter. But in1984, another incumbent, Ronald Reagan, used the debates to defuse criticism of his advancing age.
"You are already the oldest president in history," the questioner asked. He was 73 at the time.
"I am not going to exploit for political purposes my opponent's youth and inexperience," Reagan said.
Walter Mondale, Reagan's opponent, later said he was smiling, "(but) I knew he had gotten me there."
Other lessons: It may be best not to start your opening statement this way:
"Who am I? Why am I here?"
That's what Admiral William Stockdale, Ross Perot's running mate, said in 1992.
And don't look like you have someplace better to be -- as President George H.W. Bush did that same year, when he checked his watch during a question.
Don't crowd your opponent. Vice President Al Gore came uncomfortably close to George W. Bush in 2000.
Finally, be careful who you compare yourself to.
"I have as much experience in Congress as Jack Kennedy did when he sought the presidency," Dan Quayle said as a vice presidential candidate in 1988 debate against Lloyd Bentsen.
"I knew Jack Kennedy," Bentsen famously said. "Jack Kennedy was a friend of mine. Senator, you're no Jack Kennedy."
In this era of scripted and stage-managed candidates, the debates offer something increasingly dangerous -- the chance of a spontaneous moment.