A lawyer shall not bring or defend a proceeding, or assert or controvert an issue therein, unless there is a basis in law and fact for doing so that is not frivolous, which includes a good faith argument for an extension, modification or reversal of existing law. A lawyer for the defendant in a criminal proceeding, or the respondent in a proceeding that could result in incarceration, may nevertheless so defend the proceeding as to require that every element of the case be established.
N.M. R. Prof'l. Cond. 16-301
Committee commentary. -
 The advocate has a duty to use legal procedure for the fullest benefit of the client's cause, but also a duty not to abuse legal procedure. The law, both procedural and substantive, establishes the limits within which an advocate may proceed. However, the law is not always clear and never is static. Accordingly, in determining the proper scope of advocacy, account must be taken of the law's ambiguities and potential for change.
 The filing of an action or defense or similar action taken for a client is not frivolous merely because the facts have not first been fully substantiated or because the lawyer expects to develop vital evidence only by discovery. What is required of lawyers, however, is that they inform themselves about the facts of their clients' cases and the applicable law and determine that they can make good faith arguments in support of their clients' positions. Such action is not frivolous even though the lawyer believes that the client's position ultimately will not prevail. The action is frivolous, however, if the lawyer is unable either to make a good faith argument on the merits of the action taken or to support the action taken by a good faith argument for an extension, modification or reversal of existing law.
 The lawyer's obligations under this rule are subordinate to federal or state constitutional law that entitles a defendant in a criminal matter to the assistance of counsel in presenting a claim or contention that otherwise would be prohibited by this rule.
[Adopted by Supreme Court Order No. 08-8300-029, effective November 3, 2008.].
ANNOTATIONS The 2008 amendment, approved by Supreme Court Order No. 08-8300-029, effective November 3, 2008, added the requirement that a defense or claim must be based in law and fact. Compiler's notes. - The old ABA Comment was replaced by the 2008 committee commentary. Requirement of "good faith argument". - Although this rule recognizes that the law is not static, and that "account must be taken of the law's ambiguities and potential for change" a case upon which a lawyer relies to argue for the extension, modification, or reversal of existing law, must say what the lawyer says it says and, when relying upon an exception to a general rule of law, the position the lawyer asserts must either come within the exception, or provide a cogent argument for broadening the exception. In re Richards, 1999-NMSC-030, 127 N.M. 716, 986 P.2d 1117. There is no exception to this rule for occasions when an attorney might wish to pursue an invalid claim simply to see whether the opposing party might offer something in the way of settlement. In re Bloomfield, 1996-NMSC-017, 121 N.M. 605, 916 P.2d 224. Frivolous lawsuit. - Where respondent, representing a client who was charged with incest, criminal sexual contact, and criminal sexual penetration of his granddaughter, knew that client had committed incest, but filed a frivolous civil lawsuit on behalf of client against client's accusers alleging that client had been falsely accused and prosecuted was sufficient evidence to support the conclusion that respondent did not have a good faith basis for bringing the lawsuit. In re Venie, 2017-NMSC-018. Lawsuit on behalf of fictitious individual. - Where an attorney, in an attempt to avoid summary judgment on claim preclusion grounds, knowingly made false statements to the district court regarding the identity of his client, representing that his client was not the same person as the plaintiff in a previously filed federal lawsuit based on events that occurred at the Roosevelt County Detention Center (RCDC), there was sufficient evidence to support the disciplinary board's determination that the attorney violated this rule by filing frivolous claims on behalf of an apparently fictitious individual with whom the attorney never spoke before filing suit and who was not even incarcerated at RCDC on the date in question. In re Dixon, 2019-NMSC-006. Meritless defense. - In a personal injury action for damages resulting from a pharmacist filling a child's prescription for Ritalin with methadone, where attorney, who had prior knowledge that her client's records indicated that the prescription at issue had been mis-filled, who recommended that the client admit liability, and who relied on representations from the pharmacist, pharmacy manager and out-of-state counsel for the pharmacy that the missing drugs could be accounted for and followed their advise to investigate other possible sources for the methadone that injured the plaintiff rather that using the attorney's independent judgment, and who proceeded to defend the case that was contrary to the evidence the attorney had found and that the attorney had not provided in discovery, the attorney pursued a meritless defense. In re Estrada, 2006-NMSC-047, 140 N.M. 492, 143 P.3d 731.