Colorado Court Rules
Colorado Rules of Professional Conduct
As amended through Rule Change 2018(4), effective March 15, 2018
A lawyer shall not:
(a) unlawfully obstruct another party's access to evidence or unlawfully alter, destroy or conceal a document or other material having potential evidentiary value. A lawyer shall not counsel or assist another person to do any such act;
(b) falsify evidence, counsel or assist a witness to testify falsely, or offer an inducement to a witness that is prohibited by law;
(c) knowingly disobey an obligation under the rules of a tribunal except for an open refusal based on an assertion that no valid obligation exists;
(d) in pretrial procedure, make a frivolous discovery request or fail to make reasonably diligent effort to comply with a legally proper discovery request by an opposing party;
(e) in trial, allude to any matter that the lawyer does not reasonably believe is relevant or that will not be supported by admissible evidence, assert personal knowledge of facts in issue except when testifying as a witness, or state a personal opinion as to the justness of a cause, the credibility of a witness, the culpability of a civil litigant or the guilt or innocence of an accused; or
(f) request a person other than a client to refrain from voluntarily giving relevant information to another party unless:
(1) the person is a relative or an employee or other agent of a client and the lawyer is not prohibited by other law from making such a request; and
(2) the lawyer reasonably believes that the person's interests will not be adversely affected by refraining from giving such information.
Cite as RPC 3.4
History. Entire Appendix repealed and readopted April 12, 2007, effective January 1, 2008.
 The procedure of the adversary system contemplates that the evidence in a case is to be marshaled competitively by the contending parties. Fair competition in the adversary system is secured by prohibitions against destruction or concealment of evidence, improperly influencing witnesses, obstructive tactics in discovery procedure, and the like.
 Documents and other items of evidence are often essential to establish a claim or defense. Subject to evidentiary privileges, the right of an opposing party, including the government, to obtain evidence through discovery or subpoena is an important procedural right. The exercise of that right can be frustrated if relevant material is altered, concealed or destroyed. Applicable law in many jurisdictions makes it an offense to destroy material for purpose of impairing its availability in a pending proceeding or one whose commencement can be foreseen. Falsifying evidence is also generally a criminal offense. Paragraph (a) applies to evidentiary material generally, including computerized information. Applicable law may permit a lawyer to take temporary possession of physical evidence of client crimes for the purpose of conducting a limited examination that will not alter or destroy material characteristics of the evidence. In such a case, applicable law may require the lawyer to turn the evidence over to the police or other prosecuting authority, depending on the circumstances.
 With regard to paragraph (b), it is not improper to pay an expert or non-expert's expenses or to compensate an expert witness on terms permitted by law. It is improper to pay any witness a contingent fee for testifying. A lawyer may reimburse a non-expert witness not only for expenses incurred in testifying but also for the reasonable value of the witness's time expended in testifying and preparing to testify, so long as such reimbursement is not prohibited by law. The amount of such compensation must be reasonable based on all relevant circumstances, determined on a case-by-case basis.
 Paragraph (f) permits a lawyer to advise relatives and employees of a client to refrain from giving information to another party because the relatives or employees may identify their interests with those of the client. See also Rule 4.2. However, other law may preclude such a request. See Rule 16, Colorado Rules of Criminal Procedure.