ER 4.4. Respect for Rights of Others
(a) In representing a client, a lawyer shall not use means that have no substantial purpose other than to embarrass, delay, or burden any other 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 and knows or reasonably should know that the document or electronically stored information was inadvertently sent shall promptly notify the sender and preserve the status quo for a reasonable period of time in order to permit the sender to take protective measures.
 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 others. It is impracticable to catalogue all such rights, but they include legal restrictions on methods of obtaining evidence from others and unwarranted intrusions into privileged relationships, such as the client-lawyer relationship.
 Paragraph (b) recognizes that lawyers sometimes receive a document
s 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 accidentally 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 ER requires the lawyer to stop reading the document, to make no use of the document, and 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 the document or electronically stored information, is a matter of law beyond the scope of these ERs, as is the question of whether the privileged status of a document or electronically stored information has been waived. Similarly, this ER 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 ER, “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. A receiving lawyer who discovers metadata embedded within a document or electronically stored communication and who knows or reasonably should know that the metadata reveals confidential or privileged information has a duty to comply with the procedures set forth in ER 4.4(b).
 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 ERs 1.2 and 1.4.