Rubin Estate v Rubin Estate 2017 ONSC 1404 dealt with an application of prohibiting Lawyer from acting for her siblings and mother who were being sued by one daughter.
The lawyer in question had previously given US tax advise on a ” no names basis” and the court found that this did not warrant sufficient grounds to prohibit the lawyer from acting as counsel.
2 Lawyers can be prohibited from acting against a person where:
a. the lawyer has received relevant confidential information from the person attributable to a lawyer client relationship; and
b. there is a risk that the lawyer will use the person’s confidential information to the prejudice of the person.
Ontario v. Chartis Insurance Co. of Canada, 2017 ONCA 59 (Ont. C.A.) (CanLII) at para.33.
In the leading Supreme Court of Canada case on this topic, MacDonald Estate v. Martin,  3 S.C.R. 1235 (S.C.C.), Mr. Justice Sopinka adverted to this very issue.
In discussing the need to protect the client’s confidentiality during a motion to remove opposing counsel, Sopinka J. held that clients cannot be required to prove that their former lawyer had confidential information because “[i]n order to explore the matter in depth may require the very confidential information for which protection is sought to be revealed.”
To avoid this conundrum, the Supreme Court of Canada created a rule under which all that a former client needs to do is to show that there was a previous relationship between the client and the lawyer related to the lawyer’s current, adverse retainer, and the court will then infer that confidential information was imparted to the lawyer by the former client unless the lawyer proves otherwise.
Moreover, if the lawyer wants to try to prove that no confidential information was disclosed to him or her, the lawyer’s burden “must be discharged without revealing the specifics of the privileged communication.” See MacDonald Estate at pp. 1260 and 1261.
Accordingly, I do not have to assess whether a lawyer who receives information on a “no names” basis has a duty akin to a law firm marketing its services to a potential client as discussed in Ainsworth Electric Co. v. Alcatel Canada Wire Inc., 1998 CarswellOnt 2162 (Ont. Master).
Nor do I have to try to balance the applicant’s right to a lawyer of her choosing against the respondents’ right to protection of their confidences in a solicitor client relationship. In light of the disclosure of the email, there is no more confidential information in the hands of the applicant’s firm and therefore there is no risk of the applicant’s lawyer illicitly using any confidential information in his firm’s possession.