Gary A. Olson of Idaho State University has a good article on "The Limits of Academic Freedom" at the Chronicle of Higher Ed. An excerpt:
One chair described a senior professor who missed a substantial number of her classes. When confronted with evidence of her absenteeism, she told her chair that as an academic she had the freedom to conduct her courses in any way she deemed appropriate. [...] The magical incantation—"I'm protected by academic freedom"—is thought to offer instant indemnity. [...] Some people confuse the constitutional concept of freedom of speech with the less grandiose notion of academic freedom, but they are two distinct concepts. Academic freedom is limited to the confines of academic discourse while free speech is a broad constitutional right central to our democratic system of government. [...] Academic freedom is a right we should all cherish because it ensures an environment of free inquiry. That is precisely why we must guard against attempts to make the concept so limitless, so capacious, that it loses its power to protect the academic enterprise. When academic freedom becomes all things to all people, then it becomes nothing at all.