Yes, in some cases it can be appropriate to cancel a callback interview you have already scheduled. If you are in the fortunate position of receiving an offer for next summer, you may want to consider cancelling any remaining callbacks at firms you are less excited about. This will save time and money for both you and the firm, and may create opportunities for some of your Georgetown Law classmates. If you are not sure about how the other firms compare to the one(s) you have the offer from, be sure to speak with your counselor to talk through the pros and cons.
The process to cancel can be done as follows:
1. Call the recruiter and let her know that you will be pursuing another option for next summer but that you really appreciated their consideration and hope you can remain in touch (it's always good to keep bridges intact in this profession);
2. After the call, send an email to the recruiter to confirm your conversation and withdrawal of your application (thank them again for their consideration -- it may be repetitive but this email will probably be forwarded to the hiring partner or committee); and
3. If your screener interviewer or someone else has been in constant communication with you, you should extend the courtesy of letting them know your final decision -- an email should be fine for this purpose.
When cancelling a callback, it is essential that you are professional and gracious when speaking to the firm’s recruiting staff and that you give the firm as much notice as possible. If it is a last minute cancellation, and travel arrangements have been made, speak to an OCS counselor about how to handle the situation. In this case, you will want to make clear that you will honor your commitment and attend the interview, but give the firm the option of choosing to cancel.
Also, for statistics purposes, many recruiters may ask where you decided to go instead of their firm. This is a normal request, so you may want to be ready to disclose where you will be going next summer, or at least which firms you are deciding between.