In the US, lawyers are ethically prohibited from contacting a party the lawyer knows is represented by counsel regarding a matter that is the subject of that representation. There’s a spirited and enlightening Redline query discussion underway about the practical application of this rule in the transactional context (one in which member jayparkhill commented: “This is super-interesting. It's always good to pull up the rules every once in a while rather that relying on what we think they say.”)
The rule is not without its detractors. Professor Leubsdorf insightfully questions why the consent of the represented party is insufficient to waive operation of the rule. The rule anoints the lawyer as the absolute arbiter of whether the client may contact the other side's lawyer, setting up an inherent conflict of interest:
John Leubsdorf, Communicating with Another Lawyer’s Client: The Lawyer’s Veto and the Client’s Interests (U. Penn L. Rev. 1979).
If the lawyer is paid by the hour, he will profit if all communications go through him. In addition, direct communication with opposing counsel may reveal to a client that his lawyer is lazy or uninformed, or that the client’s prospects of success differ from what his lawyer has led him to believe. These possibilities may well bias the lawyer against consenting to direct communications with his client.
All in all, I do not believe that it is justifiable to empower lawyers to decide whether their clients will be able to talk with other lawyers. The rule so providing is not rooted in antiquity, serves no compelling interest, and was probably influenced by an improper desire to protect lawyers against their own clients. Granting the possible dangers of uncounseled communications, it by no means follows that the lawyer is best suited to decide whether a client should risk them, particularly when the client can obtain the lawyer's advice before deciding. In its present form, [the no-contact rule] gives lawyers unnecessary power over their clients' decisions and may lead to conscious or unconscious subordination of the interests of the clients.
Geoffrey C. Hazard, Jr. and Dana Remus Irwin, in Toward a Revised 4.2 No-Contact Rule (Hastings L.J. 2009), have similarly noted the paternalism exhibited by the rule and how it can work against the client’s interests: “By placing complete control of communications in the lawyer’s hands, this approach presumes the role of the traditional, faithful lawyer. But fulfillment of this role is contradicted by the very initiative the client is undertaking—contacting another lawyer after deciding a retained lawyer is not serving the client’s best interests.”
The authors propose reforms to the rule only after first making the case for the rule’s repeal:
There is a strong argument that the Rule should be repealed and its work done by Rule 4.3—that is, a lawyer should not present himself to a non-client as disinterested, should not give legal advice (except to consult another lawyer), and should not negotiate with a person he knows to be represented.