I've run into a small potential problem with my law school applications. I recently had a former supervisor write a letter of recommendation for me. I asked that before he sent it to LSAC, he put it on our agency's official letterhead. He said he had to get it approved first by his higher-ups, but that he would be happy to do so. I found out today that my agency denied the request and will not allow any of my recommenders to utilize the official letterhead for their respective recommendations. I know that you say that letters in general very seldom changed your mind one way or another about a law school applicant, but is this something that can realistically hurt me in the process, or is it small potatoes? Is it worth explaining in a separate attachment? Or is this something that happens often enough that admissions officers don't think twice about it?
Let me start with the bottom line to spare you some anxiety: Don't lose sleep over this.
In general, recommendation letters should be submitted on letterhead if possible. That's because recommenders are presumably writing (and giving their opinions about you) in their professional capacities, either as your professors or as your supervisors. Letterhead reflects the fact that they are wearing those official hats when offering their opinions.
However, it's not uncommon -- especially in the working world -- for organizations and companies to ban recommendation letters on their letterhead altogether, largely for fear of being sued. What if a recommender says unflattering things about you on the official letterhead for Deep Pockets, Inc. and you dial 1-800-Ambulance-Chaser? You can imagine that a lot of companies don't want to have to deal with that possible hassle, and that leaves well-meaning professional recommenders having to write their letters without the benefit of their official letterhead. So be it. Blame it on the lawyers.
Here's another variation: Sometimes applicants ask former supervisors for letters when those people have themselves moved on and no longer work for XYZ. In that case, the recommender couldn't write on XYZ's official letterhead even if he wanted to, because he no longer works for there, and he no longer represents them in an official capacity. So it's perfectly fine for him to fire up a plain old Word doc and explain that he used to supervise you when you both worked at XYZ.
Ultimately, you aren't expected to explain why a letter might not be on letterhead, not least because many applicants never get to see their recommendation letters, so there's no burden on you to explain what kind of stationery it's on. If schools get those non-letterhead recommendations and have any questions about them, they'll just pick up the phone and call the recommender (as they do with any recommendation letter they have questions about), and he can tell them either "Damn lawyers," or "I don't work there anymore."
Hope that helps. Good luck with your applications.
Former Dean of Admissions at the University of Chicago Law School and a recovering lawyer, Anna Ivey founded Ivey Consulting to help college, law school, and MBA applicants navigate the admissions process. Read more admissions tips in The Ivey Guide to Law School Admissions, recently updated and available as an e-book. Follow Anna on Twitter (@annaivey).