Ethics

Although the theoretical answer to this question is "no", context is crucial.  An undertaking on behalf of your client will only be enforceable against the client and not you, provided you had express instructions to give it. 
See: Marsden v Marsden [1972] Fam 280 at 287. 

However you should never leave room for doubt where an undertaking is involved.  If you do not intend to be bound personally because the undertaking is given on behalf of the client, you should expressly state that fact.

• If you are found to have given a personal undertaking, you are bound by it.  Failure to satisfy the undertaking may amount to professional misconduct.
• Even if you gave the undertaking on the basis of your client's instructions, it is no excuse that the client's instructions later changed.  You will still be bound to honour the undertaking and to follow your client's new (lawful) instructions.
• You may seek reimbursement from your client.
• To avoid doubt, instead of saying:
  "I undertake on behalf of my client".
  You should say:
  "I am instructed that my client undertakes”.

If you ever find yourself called upon to give an undertaking, you should pay careful attention to general principles of professional conduct as well as the specific obligations of the Professional Conduct and Practice Rules 2005 (pdf).
Note: Rules 22 and 27 confirm undertakings may be given expressly or by necessary implication.

In many cases, the answer to this question is yes.  You must therefore educate your staff about the significance of solicitors' undertakings.
Rule 27.3 states:
…”an undertaking given by an employee of a practitioner, whether or not the employee is a practitioner, shall be deemed to be a personal undertaking given by the employer practitioner unless the employee, being a practitioner, makes expressly clear the undertaking is the employee's personal undertaking and not that of the employer”.
Rule 22.2A applies the same rule to undertakings given by an employee to another solicitor in the course of legal practice.  Note:  This is a Victorian-specific provision and goes beyond the scope of the National Model Rules on which our 2005 practice rules are based.

Generally, there is nothing to prevent you from asking another solicitor to give an undertaking, although you cannot force them to do so.  Likewise no one may force you to give an undertaking in the course of your practice.

You may not ask another solicitor (or another solicitor's employee) to give an undertaking which relies on a third party whose cooperation cannot be guaranteed.  To do so would be an express breach of Rule 22.3 Professional Conduct and Practice Rules 2005 (pdf).

This issue is currently under consideration by the Ethics Committee.  It was brought to the Committee's attention in two unrelated matters:

• A defendant to child sex allegations proposed settlement on the basis of the plaintiff's solicitor undertaking not to act in any other matter against the same defendant.
• A financial adviser defending allegations of professional negligence proposed to settle with one plaintiff on the basis the plaintiff’s solicitor would refuse to act for other potential plaintiffs.

A request for such an undertaking raises serious ethical issues:

• It creates an unavoidable conflict between the interests of the undertaking solicitor's client (settlement) and the solicitor’s own interests (not to restrain future trade). 
• It attempts to bind a third party (the solicitor) as part of the terms of settlement.

Guidelines are under consideration.  Practitioners wishing to express a view should contact ethics@liv.asn.au.