(a) Except as provided in section (b) of this Rule, an attorney shall not represent a client if the representation involves a conflict of interest. A conflict of interest exists if:

(1) the representation of one client will be directly adverse to another client; or

(2) there is a significant risk that the representation of one or more clients will be materially limited by the attorney's responsibilities to another client, a former client or a third person or by a personal interest of the attorney.

(b) Notwithstanding the existence of a conflict of interest under section (a) of this Rule, an attorney may represent a client if:

(1) the attorney reasonably believes that the attorney will be able to provide competent and diligent representation to each affected client;

(2) the representation is not prohibited by law;

(3) the representation does not involve the assertion of a claim by one client against another client represented by the attorney in the same litigation or other proceeding before a tribunal; and

(4) each affected client gives informed consent, confirmed in writing.