Colorado Court Rules
Colorado Rules of Professional Conduct
Transactions with Persons Other Than Clients
As amended through Rule Change 2018(6), effective April 12, 2018
(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 relating to the representation of the lawyer's client and knows or reasonably should know that the document was inadvertently sent shall promptly notify the sender.
(c) Unless otherwise permitted by court order, a lawyer who receives a document relating to the representation of the lawyer's client and who, before reviewing the document, receives notice from the sender that the document was inadvertently sent, shall not examine the document and shall abide by the sender's instructions as to its disposition.
Cite as RPC 4.4
History. Entire Appendix repealed and readopted April 12, 2007, effective January 1, 2008.
 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 documents that were mistakenly sent or produced by opposing parties or their lawyers. A document is inadvertently sent when it is accidentally transmitted, such as when an e-mail 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 was sent inadvertently, then this Rule requires the lawyer to promptly notify the sender in order to permit that person to take protective measures. Paragraph (c) imposes an additional obligation on lawyers under limited circumstances. If a lawyer receives a document and also receives notice from the sender prior to reviewing the document that the document was inadvertently sent, the receiving lawyer must refrain from examining the document and also must abide by the sender's instructions as to the disposition of the document, unless a court otherwise orders. Whether a lawyer is required to take additional steps beyond those required by paragraphs (b) and (c) is a matter of law beyond the scope of these Rules, as is the question of whether the privileged status of a document has been waived. Similarly, this Rule does not address the legal duties of a lawyer who receives a document that the lawyer knows or reasonably should know may have been inappropriately wrongfully obtained by the sending person.
For purposes of this Rule, "document" 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.
 In the circumstances of paragraph (b), some lawyers may choose to return an inadvertently sent document. Where a lawyer is not required by applicable law or paragraph (c) to do so, the decision to voluntarily return such a document is a matter of professional judgment ordinarily reserved to the lawyer. See Rules 1.2 and 1.4.