I'm a recent graduate currently looking for work, so I've been going on several interviews lately. I have a list of about five references from previous jobs and internships that I bring to the interviews.
On a recent interview, when I handed my list of references to the hiring manager, he laughed a bit and said that he knows and is an "old friend" of one of my references. He then told me that he wouldn't contact that reference. It didn't sound like an offhand remark, either. It sounded like he had a solid reason for not wanting to discuss my work performance with his friend, but I didn't want to ask why during the interview. If the roles were switched, my friend would probably be the first person I would contact, because I know and trust the word of my friends in the industry.
If a hiring manager is evaluating a candidate, and the candidate's list of references includes a friend of the hiring manager, are there any ethical or legal reasons the manager should not contact the friend to discuss the candidate?