Linten Developments Ltd. v. Kirschner Mountain Estates Ltd.
 A lawyer, and by extension a law firm, owes a duty of loyalty to
clients. This duty has three salient dimensions: (1) a duty to avoid conflicting
interests; (2) a duty of commitment to the client’s cause; and (3) a duty of
candour: Neil, at para. 19. I will consider each in turn.
The law of conflicts is mainly concerned with two types of prejudice:
prejudice as a result of the lawyer’s misuse of confidential information
obtained from a client; and prejudice arising where the lawyer “soft peddles”
his representation of a client in order to serve his own interests, those of
another client, or those of a third person.
The second main concern, which arises with respect to current clients,
is that the lawyer be an effective representative — that he serve as a zealous
advocate for the interests of his client. The lawyer must refrain “from being in
a position where it will be systematically unclear whether he performed his
fiduciary duty to act in what he perceived to be the best interests” of his client:
D. W. M. Waters, M. R. Gillen and L. D. Smith, eds., Waters’ Law of Trusts in
Canada (4th ed. 2012), at p. 968. As the oft-cited Lord Brougham said, “an
advocate, in the discharge of his duty, knows but one person in all the world,
and that person is his client”: Trial of Queen Caroline (1821), by
J. Nightingale, vol. II, The Defence, Part I, at p. 8.
Effective representation may be threatened in situations where the
lawyer is tempted to prefer other interests over those of his client: the
lawyer’s own interests, those of a current client, of a former client, or of a third
person: Neil, at para. 31. This appeal concerns the risk to effective
representation that arises when a lawyer acts concurrently in different matters
for clients whose immediate interests in those matters are directly adverse.
This Court has held that concurrent representation of clients directly adverse
in interest attracts a clear prohibition: the bright line rule.
In Neil, this Court (per Binnie J.) stated that a lawyer may not
represent a client in one matter while representing that client’s adversary in
another matter, unless both clients provide their informed consent. Binnie J.
articulated the rule thus:
The bright line is provided by the general rule that a lawyer may not
represent one client whose interests are directly adverse to the
immediate interests of another current client — even if the two
mandates are unrelated — unless both clients consent after receiving
full disclosure (and preferably independent legal advice), and the
lawyer reasonably believes that he or she is able to represent each
client without adversely affecting the other. [Emphasis in original;
The duty of commitment is closely related to the duty to avoid
conflicting interests. In fact, the lawyer must avoid conflicting interests
precisely so that he can remain committed to the client. Together, these
duties ensure “that a divided loyalty does not cause the lawyer to ‘soft peddle’