4.4 Respect for Rights of Third Persons; Inadvertent Disclosures
(a) In representing a client, a lawyer shall not use means that have no substantial purpose other than to embarrass, delay, or burden a third person, or use methods of obtaining evidence that violate the legal rights of such a person.
(b) A lawyer who receives a writing and has reasonable cause to believe the writing may have been inadvertently disclosed and contain confidential information or be subject to a claim of privilege or of protection as trial preparation material:
(1) shall not read the writing or, if he or she has begun to do so, shall stop reading the writing;
(2) shall notify the sender of the receipt of the writing; and
(3) shall promptly return, destroy or sequester the specified information and any copies.
The recipient may not use or disclose the information in the writing until the claim is resolved, formally or informally. The sending or receiving lawyer may promptly present the writing to a tribunal under seal for a determination of the claim.
 Responsibility to a client requires a lawyer to subordinate the interests of others to those of the client, but that responsibility does not imply a lawyer may disregard the rights of third persons. It is impractical to catalogue all such rights, but they include legal restrictions on methods of obtaining evidence from third persons and unwarranted intrusions into privileged relationships, such as the client-lawyer relationship. See also Rule 3.4, setting forth rules regarding Fairness to Opposing Party and Counsel.
 Paragraph (b) recognizes lawyers sometimes receive writings mistakenly sent or produced by opposing parties or their lawyers. If a lawyer knows or reasonably should know that such a received writing contains confidential information or may be subject to a claim of privilege, this Rule requires that the lawyer not read the writing, and return, sequester or destroy the writing and any copies, making no further use of it. Whether the privileged status of a writing has been waived is a matter of law beyond the scope of these Rules. For purposes of these Rules, “writing” includes e-mail or other electronic modes of transmission subject to being read or put into readable form (see Rule 1.0(n)).
 Some lawyers may choose to return a document unread, for example, when the lawyer learns before receiving the document that it was inadvertently sent to the wrong address. When a lawyer is not required by applicable law to do so, the decision to voluntarily return such a document is a matter of professional judgment ordinarily reserved to the lawyer. It is not a violation of a duty to a client or of these Rules of Professional Conduct to return a document in such circumstances.
 The fact a writing contains metadata does not necessarily mean the sending lawyer intended the metadata be disclosed, notwithstanding the fact the ostensible writing may have been disclosed intentionally. The embedded metadata, if it contains confidential information, or is subject to a claim of privilege or of protection as trial preparation material, may be deemed to be inadvertently disclosed, and thus subject to paragraph (b).
Model Rule 4.4(a) (2002) substantively is in accord with M. Bar R. 3.7(a), as well as with the Maine Attorney’s Oath, 4 M.R.S. §806 (stating that, as lawyers, we should not “wittingly or willingly promote or sue any false, groundless or unlawful suit nor give aid or consent to the same”). The Task Force thought the Model Rule provided a sound articulation of the idea found in M. Bar R. 3.7(a), and thus recommended its adoption.
Model Rule 4.4(b) (2002) addresses a lawyer’s responsibility in the event he or she receives an inadvertently sent writing. The Task Force discussed four alternative formulations of this rule: The Model Rule (2002), the rule in Maine, a version of the rule adopted in New Jersey (the “New Jersey Rule”), and a rule tracking the approach taken in proposed Federal Civil Procedure Rule 26(b)(5)(B) (Dec. 1, 2006).
The Model Rule, originally adopted in 2002, merely requires the lawyer “promptly notify the sender” and provides lawyers with no further guidance. While there is no further obligation imposed upon a lawyer under that rule, other law may impose additional obligations. A number of states, including New Jersey, have adopted a rule offering lawyers further guidance. The New Jersey Rule directs an attorney who has received an inadvertently disclosed writing to not read the writing or, if he or she has begun to do so, stop reading, promptly notify and follow the instructions of the sender and make no further use of the writing.
The Task Force also reviewed Federal Civil Procedure Rule 26(b)(5)(B) (Dec. 1, 2006), in light of the language in the New Jersey Rule. The Task Force recognized the approach taken in Federal Civil Procedure Rule 26(b)(5)(B) allows for a case-by-case determination of the effect of disclosure of confidential or protected writings. It represents an attempt to permit parties to use reasonable measures in discovery to protect their privileged communications. It further recognizes when a writing is disclosed, there may be competing views with respect to whether the writing is confidential or privileged. The version of Rule 4.4(b) recommended by the Task Force places the obligation on the receiving party who realizes the disclosure error to stop reading, to notify the producing party, and to return, destroy or sequester it, pursuant to instructions, or to seal it pending resolution of a claim of privilege or protection. The lawyer is not allowed to make any further use of it unless the claim of protection is resolved to allow such further use. The resolution may be accomplished formally (by a tribunal) or informally (through negotiation between the parties). The inclusion of an informal means of resolving the issue of a claim of protection is an acknowledgement that in certain situations, it may not be feasible, financially or otherwise, to involve a tribunal.
The Task Force recommended a formulation of Rule 4.4(b) different from Maine Ethics Opinion No. 172, which has been the governing law in Maine since the Maine Supreme Judicial Court’s decision in Corey v. Norman Hanson & DeTroy, 1999 ME 196, 742 A.2d 933. Corey, held an inadvertently disclosed memorandum protected by the attorney-client privilege should be returned by the receiving attorney to the disclosing attorney, and no further use should be made of it. The Task Force’s recommendation also departs from the practical impact of the rule articulated by the Federal District Court in FDIC v. Singh, 140 F.R.D. 252 (D. Me. 1992) (stating any intentional or inadvertent disclosure of privileged material is an automatic waiver of the attorney-client privilege). In both of these cases, the courts rejected a case-by-case determination of when the inadvertent disclosure of a writing is a waiver of a privilege. The Task Force thought it wise to permit lawyers, who were in dispute with respect to a claim of a writing’s privilege, to seek a neutral third party’s opinion, or to attempt to resolve the issue through less formal means. The Task Force believed, in situations involving inadvertent disclosures, a case-by-case determination would best balance the competing interests of the parties.
The Task Force also recognized the advent of new technologies may alter the nature of some inadvertent disclosures. For example, while a writing may have been intentionally disclosed by a lawyer, the revelation of embedded metadata may rise to the level of an inadvertent disclosure. If such metadata contains confidential information, or is subject to a claim of privilege or of protection as trial preparation material, it is subject to paragraph (b).
The Task Force stressed the importance of making it clear to lawyers admitted in other jurisdictions that the Maine Rule of Professional Conduct 4.4(b), as recommended, is a departure from the 2002 Model Rule. Lawyers who have been practicing in Maine under Maine Ethics Opinion No. 172 must also be made aware that Rule 4.4(b) represents a different approach to dealing with the issue of inadvertently disclosed writings.