An adjunct professor at Metro State College in Denver set his students the task of doing a piece of work critical of Sarah Palin. He asked them 'to write an essay to contradict what he called the "fairy tale image of Palin" presented at the Republican National Convention.' A student complained and this has led to an investigation by the college.
In itself, there's nothing wrong with the assignment. Asking students to undertake such a critical exercise about any politician might just be a way of testing their linguistic and analytical powers. It all depends on what other assignments they are given. That is, are they asked to do this sort of thing about other politicians as well? Was it conceived as a critical exercise only, or as a way of promoting the teacher's own political preferences? That the assignment was later revised to allow students to write on any of the candidates suggests that he and/or the college didn't feel that all was well as things stood.