This ABA Journal column describes some interesting ethical challenges arising from the increasing prevalence of verein-style law firms.In a nutshell, a firm set up as a verein typically uses a common name (e.g., DLA Piper), but each office is administratively and financially separate from the other offices. The ABA Journal column notes that this kind of structure raises possible problems under Model Rule 1.5(e), depending on how the firm handles the origination of business and the referral of matters among offices.
Another interesting question -- not directly addressed in the column -- relates to Rule 5.4. For example, imagine that a verein-style firm has offices in New York and London, and the London office has nonlawyer partners. The New York office may be asked to make certain cost contributions to a common fund for, say, marketing that benefits all offices. Depending on how the common fund is administered (e.g., Is it just for marketing? Or is "cost" sharing used in such a way that it rewards particular offices or lawyers for their origination of business?), such contributions could raise problems under Rule 5.4. (Somewhat related issues are addressed in ABA Formal Opinion 464. See also here.)
I suspect that we'll be hearing more about the ethics issues associated with vereins in the years ahead.