Rule 3.3—Candor to Tribunal
(a) A lawyer shall not knowingly:
(1) Make a false statement of fact or law to a tribunal or fail to correct a false statement of material fact or law previously made to the tribunal by the lawyer, unless correction would require disclosure of information that is prohibited by Rule 1.6;
(2) Counsel or assist a client to engage in conduct that the lawyer knows is criminal or fraudulent, but a lawyer may discuss the legal consequences of any proposed course of conduct with a client and may counsel or assist a client to make a good-faith effort to determine the validity, scope, meaning, or application of the law;
(3) Fail to disclose to the tribunal legal authority in the controlling jurisdiction not disclosed by opposing counsel and known to the lawyer to be dispositive of a question at issue and directly adverse to the position of the client; or
(4) Offer evidence that the lawyer knows to be false, except as provided in paragraph (b). A lawyer may refuse to offer evidence, other than the testimony of a defendant in a criminal matter, that the lawyer reasonably believes is false.
(b) When the witness who intends to give evidence that the lawyer knows to be false is the lawyer’s client and is the accused in a criminal case, the lawyer shall first make a good-faith effort to dissuade the client from presenting the false evidence; if the lawyer is unable to dissuade the client, the lawyer shall seek leave of the tribunal to withdraw. If the lawyer is unable to dissuade the client or to withdraw without seriously harming the client, the lawyer may put the client on the stand to testify in a narrative fashion, but the lawyer shall not examine the client in such manner as to elicit testimony which the lawyer knows to be false, and shall not argue the probative value of the client’s testimony in closing argument.
(c) The duties stated in paragraph (a) continue to the conclusion of the proceeding.
http://www.dcbar.org/for_lawyers/et...onduct/amended_rules/rule_three/rule03_03.cfm