Copying as parody

I've written before about how copying can be an exercise of free speech. Recently an instance in which pure copying is deployed for critical purposes has been much in the news: Tina Fey playing Sarah Palin, delivering Palin's interview answers with the same wording and even the same inflections. This is a great subject for performance theorists: words that mean one thing in the original speaker's mouth have very different meaning in another's.