Lawyers in Ontario are regulated by the Law Society of Ontario, and the Rules of Professional Conduct set out the professional and ethical obligations to which lawyers must adhere. One of the duties relates to avoiding conflicts of interest, except in certain circumstances. Rule 3.4-5 of the Law Society of Ontario Rules of Professional Conduct sets out the rule for joint retainers and provides as follows:
“Before a lawyer acts in a matter or transaction for more than one client, the lawyer shall advise each of the clients that:
- the lawyer has been asked to act for both or all of them;
- no information received in connection with the matter from one client can be treated as confidential so far as any of the others are concerned; and
- if a conflict develops that cannot be resolved, the lawyer cannot continue to act for both or all of them and may have to withdraw completely.”
When a lawyer is approached by spouses to advise them with respect to their estate plan, the discussion invariably turns to what it means to enter into a joint retainer. In most first marriage situations, the spouses often have a shared understanding of what is to be included in each of their wills, which lends nicely to a joint retainer. However, when a lawyer is faced with the situation where “subsequent to the joint retainer only one of the spouses communicates new instructions, such as instructions to change or revoke a will, the lawyer has a duty to:
- treat the subsequent communication as a request for a new retainer and not as part of the joint retainer;
- hold the subsequent communication in strict confidence and not disclose it to the other spouse; and
- decline the new retainer, unless:
- the spouses had annulled their marriage, divorced, or permanently ended their conjugal relationship;
- the other spouse had died; or
- the other spouse was informed of the subsequent communication and agreed to the lawyer acting on the new instructions.” 
If the other spouse was informed of the subsequent communication and agreed to the lawyer acting on the new instructions, the lawyer shall obtain the spouses’ consent to act in writing.
With second or third spouses or where one spouse is less sophisticated or more vulnerable than the other, the discussion around joint retainers becomes even more critical and in some cases, the lawyer should recommend that the spouses obtain independent legal advice before the lawyer accepts the joint retainer to ensure that the spouses’ consent to the joint retainer is informed, genuine and not coerced.
Conflicts of interest arise in a number of circumstances, and joint retainers are just one example where a conflict of interest may present itself.
 The lawyer should advise both spouses of this duty at the outset of the joint retainer.