At Cliopatria, Ralph Luker discusses the "syllabus = contract" issue, complete with a legal opinion from Eugene Volokh. This website, for example, suggests that one of the key functions of a syllabus is that it "serves as a communication device and contract to shift the responsibility for learning to the student," and similar positions can be found here, here (note the phrase "binding agreement"), here, and here. My student and non-academic readers may be puzzled about why such an apparently esoteric point should be of such concern to faculty. Part of it goes to our understanding of the mutual obligations between instructor and student--something I brought up in the post on attendance. I'm not Brian Leiter, and will therefore refrain from legal philosophizing, but it's worth remembering that contract implies consent, explicit or otherwise; a student who consents to the syllabus/contract takes on, as the quotation above claims, "responsibility for learning." Once you've consented, in other words, there's no excuse--you've agreed to bide by the instructor's guidelines, and can't plausibly claim at some later date that you "didn't know" about, say, that take-home final exam (or the instructor's attendance policy). At the same time, the instructor also pledges herself to teach the material on the syllabus, make herself available at the stated office hours, and so forth. In principle, this gives both parties a say on the practice of the other. The professor can penalize deviations from the contractual agreement by that trusty weapon known as the red pen, while the student can write nasty course evaluations (although it's often the case that these don't have to do with "the contract" per se...) or, more seriously, take his case to the department chair or grievance committee.
In recent years, however, the spectre of the Litigious Undergraduate (or, more properly, the Litigious Parents of the Undergraduate) has raised her head. One of the reasons we are being urged to make our syllabi more and more explicit is that, if the syllabus is a contract, then what is or isn't on it--and/or the assignments proper--may lay the college open to lawsuits. Violate the "binding agreement," and the student may be able to take you or your college to court--over grades, academic dishonesty, assignments, whatever. The problem, as Volokh points out, is that it's not clear that syllabi truly constitute "binding agreements" in any sense that could stand up in court. In other words, we're being encouraged to "legalize" our relationships with our students, but it's not clear that what we're doing has any actual legal meaning. And I suspect that some faculty feel that the rhetoric of contract, while it might render our mutual obligations explicit, inadvertently makes the professor-student relationship more adversarial than absolutely necessary--especially if that rhetoric is driven by fear of legal action!