I've had the privilege of traveling the country speaking on conflicts in patent prosecution. Some things are pretty clear to me and those I spoke to, other things people disagreed on. I've been pretty silent here (note to others: do not agree to write 2 books in one year, do 2 new preps, and give 10 lectures), and hope to start a thread on this topic generally, and with respect to specific examples.
First example: Lawyer in prosecuting application for Client A receives an office action rejecting a claim over a prior art reference. Lawyer looks, and that reference is owned by another Client, Client B.
Is this a conflict at all? Some people say that any response by the lawyer constitutes an adverse representation, even if the firm had nothing to do with obtaining the prior patent, and even if the firm's representation of the client who owns that patent are completely unrelated to the subject matter in prosecution. Others say that, in the abstract it's not a conflict, but can become one where, for example, the lawyer would be arguing that the client's patent is invalid (say, e.g., that it lacks support for the breadth argued by the PTO). Others say that that even that isn't an adverse representation.
In the background (and subject to another post, below) are two ethics opinions which both say it's per se unethical to offer invalidity (or non-infringement) opinions to one client about another client's patent. Wrongly, they view this as "helping to invalidate" a patent. (What an opinion does is, if it's done right, help one client to establish a good faith believe that it is not infringing a valid patent; it is a shield against damages, not a sword against validity.) If you take those opinions at face value, then arguably this office action is "as adverse" as an opinion.
What sayeth you?