Students ask professors to write letters of recommendation for them. Today’s professors frequently respond by asking the student to write a first draft of the letter. Henry Farrell at CrookedTimber comments on this practice. Obviously the ethics of such a request are questionable. Furthermore it puts the student in a very difficult position. How great can you claim to be and keep a straight face, not to mention a reputation for probity?
That being said, I am not very worried about the practical repercussions. Most people, especially undergraduates, do not know how to write a very good recommendation letter. They fail to realize that such letters, to be effective, should offer very specific and pointed comparisons. Those few students who understand this fact are probably too shy to call themselves “comparable to Greg Mankiw as an undergraduate.” Nor will they write “comparable to your Professor Mediocre [fill in the name yourself!] as an undergraduate.” So if a professor asks the student to write the letter, the professor does not care about the letter or student very much. The resulting letter is likely to be very generic and thus not very effective. In addition, the professor probably has a hard time saying much about the student. This again suggests the letter will be less than overwhelming, no matter who writes it.
The really good candidates still will be able to produce credible signals of quality. They will find some professors able to make coherent and specific claims on their behalf. In fact, if professors ask the lesser students to write their own letters, the relative advantage of the very best students may rise.