The "four C's" of lawyer/client interaction

In reviewing a book "How to deal with your lawyer," Patent Baristas noted:

the 4 C’s of a lawyer’s fiduciary duty (Communication, Competence, Confidentiality, and Conflicts of Interest).

Of the last, a lawyer should not take representation of one client which conflicts with a lawyer's representation of another client.
The Pennie & Edmonds matter involving URochester and COX-2 inhibitors illustrates some of the problems that can ensue when a patent law firm has two clients in the same technological space.