A friend of mine asked me if I could be a reference for them. Both of us used to work for the same company, in the same department, until they were fired by our shared manager. Reasons were presented to the remaining developers for my friend's termination, but I wasn't (and am still not) in a position to evaluate the legitimacy of these reasons.
Anyway, like I said, this friend asked me to be a reference to them. This prospective employer called me up and asked me why they left. I don't know what my friend told them about the reasons for his departure. Certainly I could ask but, at the time of this phone call, I hadn't (because I didn't think of it).
My question is, in lieu of knowing what my friend told them for the reasons for his departure, what should I say? It seems like I have three options.
I could tell the truth - that my friend was fired and that I'm not in a position to establish the veracity of the claims made against him. I could also say that, due to internal power struggles or some such he had been planning on leaving on his own, but that the early departure took him by surprise. If my friend didn't tell this to the prospective employer then I've potentially undermined him, which I don't want to do.
I could misrepresent the circumstances and say something about how each successive year you learn less and less at a company, and that my friend left because he felt he could learn more at a new company. If my friend told the prospective employer the truth then I've potentially undermined my own credibility and usefulness as a reference.
I suppose I could also refuse to answer saying something like "it's my understanding that there are some things I am not supposed to comment on", but at the same time, if I wasn't willing to comment on things I shouldn't have volunteered to be a reference in the first place IMHO.
Ideally, I'd have consulted with my friend so that we would be on the same page, but at the time of this phone call I had not done so (like I said, I didn't think of it).
So what would have been the best strategy in this situation?