On the other hand, if you are a law professor, most people will assume you are qualified to be a law professor or that at least a small group of people in charge of hiring thought so. Your advertising falls into the category of an appeal to institutional authority. That is, if the institution from which you graduated has a good reputation -- an elite ivy league school, for example -- then you must be of similar ilk. The same is true if you feel compelled to name drop the name of your school whenever possible. (I have been told that a survey of Harvard grads in conversation found that on average "Harvard" is mentioned within the first minute.)
The problem is that this does not lower search costs but actually raises them. What we know is that some elite school grads are terrific law professors and some are awful. The same is true for non elite grads. Hanging the diploma on the wall can and often is misleading. It's a practice for those who are afraid to be identified by what they actually do.