Is a lawyer who has acted for a client by reason of conflict of interest disqualified from acting for another client?

In MacDonald Estate v. Martin, 1990 CanLII 32 (SCC), [1990] 3 S.C.R. 1235 at 1245-46 [[1991] 1 W.W.R. 705], Sopinka J. for the majority discusses the appropriate standard to be applied in determining whether a lawyer who has acted for a client is disqualified from acting for another client by reason of conflict of interest. Sopinka begins his analysis with the statement, at p. 1244: The legal profession has historically struggled to maintain the respect of the public. This has been so notwithstanding the high standards that, generally, have been maintained. When the management, size of law firms and many of the practices of the legal profession are indistinguishable from those of business, it is important that the fundamental professional standards be maintained and indeed improved. This is essential if the confidence of the public that the law is a profession is to be preserved and hopefully strengthened. Nothing is more important to the preservation of this relationship than the confidentiality of information passing between a solicitor and his or her client.