Rule 4.4. Respect for Rights of Third Persons.
(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 document or electronically stored information relating to the representation of the lawyer’s client and knows or reasonably should know that the document or electronically stored information was inadvertently sent shall promptly notify the sender.
 Responsibility to a client requires a lawyer to subordinate the interests of others to those of the client, but that responsibility does not imply that 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.
 Paragraph (b) recognizes that lawyers sometimes receive a document or electronically stored information that was mistakenly sent or produced by opposing parties or their lawyers. A document or electronically stored information is inadvertently sent when it is accidently transmitted, such as when an email or letter is misaddressed or a document or electronically stored information is accidentally included with information that was intentionally transmitted. If a lawyer knows or reasonably should know that such a document or electronically stored information was sent inadvertently, then this Rule requires the lawyer to promptly notify the sender in order to permit that person to take protective measures. Whether the lawyer is required to take additional steps, such as returning or deleting the document or electronically stored information, is a matter of law beyond the scope of these Rules, as is the question of whether the privileged status of a document or electronically stored information has been waived. Similarly, this Rule does not address the legal duties of a lawyer who receives a document or electronically stored information that the lawyer knows or reasonably should know may have been inappropriately obtained by the sending person. For purposes of this Rule, "document or electronically stored information " includes in addition to paper documents, e-mail and other forms of electronically stored information, including embedded data (commonly referred to as “metadata”), that is subject to being read or put into readable form. Metadata in electronic documents creates an obligation under this Rule only if the receiving lawyer knows or reasonably should know that the metadata was inadvertently sent to the receiving lawyer.
 Some lawyers may choose to return a document or delete electronically stored information unread, for example, when the lawyer learns before receiving it that it was inadvertently sent. Where a lawyer is not required by applicable law to do so, the decision to voluntarily return such a document or delete electronically stored information is a matter of professional judgment ordinarily reserved to the lawyer. See Rules 1.2 and 1.4.