In considering your request, I had in mind some comments that Professor Stephen Bainbridge has made about the one-sided nature of these referee requests [here is one of Bainbridge's posts on the subject, he had an earlier more extensive one that I can't find]. I thought Steve was a bit too prickly about it, but I decided to look up who the Harvard Law Review has been asking to comment on its articles in its on-line publication [Note: HLR can claim that it picks the best submitted articles from its pool regardless of authors' affiliation, but it clearly has discretion with regard to whom it invites to comment on articles].
via volokh.com
