I should not that Harry from Squaring the Globe has oft cited the Gang of 88 from the Duke lacrosse rape case as the paragons of the wackiness of liberal academia. But a very quick look at the departments where these academics held positions will give a very good idea of their motivations.
The department with the highest proportion of signatories was African & African-American Studies, with 80%. Just over 72% of the Women's Studies faculty signed the statement, Cultural Anthropology 60%, Romance studies 44.8%, Literature 41.7%, English 32.2%, Art & Art History 30.7%, and History 25%. No faculty members from the Pratt School of Engineering or full-time law professors signed the document. Departments that had no faculty members sign the document include Biological Anthropology and Anatomy, Biology, Chemistry, Computer Science, Economics, Genetics, Germanic Languages/Literature, Psychology and Neuroscience, Religion, and Slavic and Eurasian Studies. Many have criticized the group for rushing to judgment in condemning the lacrosse players, but some in the group maintain that the ad made no mention of innocence or guilt, but rather elaborated on this "social disaster."
So essentially academics from departments whose political mission had a vested interest in the guilt of the lacrosse players signed the document while members of departments where actual learning happens, on average had a slightly more balanced approach. This never gets mentioned on Fox News because it doesn't feed the right's persecution complex.