dissenting.
It is undisputed in this case that Trattler failed to disclose her expert witnesses' testimonial histories as required by Rule 26(a)(2)(B)(I). The trial court found that the nondisclosure of Dr. Schapira's testimonial history was "either willful or grossly negligent on his part." It implicitly found the same with regard to Dr. Birrer, who "attempted to exeuse his [nondisclosure] by claiming that he did not have access to his administrative calendar due to a change in employment," when he did in fact have access at the time the disclosure was due. Yet the majority takes the trial court's sanction for these willful or grossly negligent nondis-closures-that is, preclusion of the expert witnesses' testimony-off the table. Unlike the majority, I believe that expert witness preclusion is an available sanction under Rule 37(c)(1) for such willful or grossly negligent disclosure violations. In my view, under Rule 37(c)(1), if a party fails to disclose "information" required by Rule 26(a2)@) (here, the testimonial histories of expert witnesses), the trial court can preclude the party from "presenting any evidence not so disclosed" (here, the expert testimony). Because the majority reaches a contrary conclusion, I respectfully dissent from its opinion.
I.
Rule 26(a) requires a plaintiff to disclose her expert witnesses 120 days before trial. C.RCP. 26(2@q)@)(C)(ID). A disclosure of an expert witness must include, in addition to the witness's identity and "fields of expertise," C.R.C.P. 26(a)@)(A), a written report or summary. CRCP. 26(aq)(@2)(B). The report or summary must contain (1) a statement of all opinions to be expressed and the basis and reasons therefor; (2) the data considered by the expert in forming the opinions; (8) any exhibits to be used; (4) the witness's qualifications, including a list of all publications he authored within the previous ten years; (5) the compensation for the study and testimony; and, relevant to this case, (6) a listing of any other cases in which the witness has testified as an expert at trial or by deposition within the preceding four years. C.R.C.P. 26(a)(@)(B)(T)-(ID). The listing of cases must, at a minimum, provide the name of the court, whether the testimony was by deposition or at trial, the parties' names, and the case number. Carlson v. Ferris, 58 P.3d 1055, 1058 (Colo.App.2002).
*684Failure to comply with Rule 26(a) is governed by Rule 87(c)(1), which provides:
A party that without substantial justification fails to disclose information required by [Rule 26(a) ] shall not, unless such failure is harmless, be permitted to present any evidence not so disclosed at trial....
(Emphasis added.) The majority reasons that the "information" and "any evidence" are the same thing. As applied here, the majority reasons, because Trattler failed to disclose her experts' testimonial histories, Rule 37(c)(1) would not permit her to present those testimonial histories at trial. Maj. op. at 681. But, the majority continues, that sanction would make no sense in this case, because Trattler is not the one who would be seeking to present the testimonial histories at trial-the defendants would, for purposes of impeachment. Id. at 681-82. Therefore, because the preclusion sanction of Rule 37(c)(1) would be absurd in such a situation, it simply falls away, and the trial court must choose another sanction. Id.
I disagree with the majority's reading because it renders expert witness preclusion inapplicable in all but a narrow set of cases-that is, where the party has failed to disclose the witness's identity. That is because under the majority's interpretation, the "evidence" excluded and the "information" not disclosed must be the same thing, and that is only true for expert witness preclusion when the "information" is the expert witness's identity. Thus, under the majority's interpretation, if the party fails to disclose other information required by Rule 26(a)(@2)-for example, the witness's field of expertise; his opinions to be expressed; the data he considered in forming his opinions; the amount he was compensated for the testimony; or, as here, an expert's voluminous testimonial history-the trial court cannot exclude the witness, regardless of how willful or grossly negligent the nondisclosure was.
Unlike the majority, I do not believe the language of Rule 87(c)(1) compels such a result. In my view, the majority's fundamental mistake is to interpret "faillure] to disclose information required by [Rule 26(a) 1" as the equivalent of "any evidence not so disclosed" in Rule 37(c)(1). In contrast to the majority, I would interpret the first phrase as referring to the specific "information" required by Rule 26(a)(2), including an expert witness's identity, the expert's field of expertise, the data on which the expert relied, any exhibit the expert will use, the expert's testimonial history, and so on. A failure to disclose any of the information required by Rule 26(a)(2) is, as the title to Rule 26(2)(@2) suggests, a failure to "Dise-los[e] ... Expert Testimony." When read in context, the "any evidence not so disclosed" phrase refers not to the specific "information" not disclosed, but to the failure to disclose expert testimony. Under this reading, a party who does not disclose the information required by Rule 26(a)(2) faces the possibility that she will not be permitted to present her expert testimony at trial.
Moreover, the trial court's action in this case was justified under the second sentence of Rule 37(c)(1), which permits the court, upon a motion, to impose "appropriate" sane-tions "in lieu of or in addition to" witness preclusion. The sanctions of Rule 37 are thus of two kinds: those that are self-executing, and those that can be imposed based on a motion from a party. We have held that the preclusion sanction contained in the first sentence of Rule 87(c)(1) "is automatic and self-executing in the sense that a motion for sanctions filed by the opposing party is not a prerequisite to the imposition of the sancetion." Todd v. Bear Valley Vill. Apartments, 980 P.2d 973, 978 (Colo.1999). By contrast, a party may choose to file a motion for "appropriate sanctions" under Rule 37(a)(2), which occurred here. When a motion for sanctions is made, the second sentence of Rule 37(c)(1) applies, which permits the trial court to impose sanctions "[in addition to ... this sanetion," referring to the preclusion sanction contained in the first sentence. In other words, because a motion was made in this case, the trial court could have precluded the expert testimony and imposed additional sanctions.
Significantly, I could find no decision in Colorado or elsewhere adopting the majority's interpretation. On the contrary, our courts have consistently permitted expert witness preclusion for failure to comply with *685any disclosure requirement of Rule 26(a)(2). See, e.g., Woznicki v. Musick, 119 P.3d 567, 575 (Colo.App.2005) ("If the party offering the testimony fails to provide sufficient information about the proposed expert's qualifications or opinions, the trial court has broad discretion to determine sanctions, including disallowing the expert's testimony."); Svendsen v. Robinson, 94 P.3d 1204, 1208 (Colo.App.2004) (holding that trial court did not abuse discretion when it precluded expert who failed to disclose prior testimony); Carlson v. Ferris, 58 P.3d 1055, 1058-59 (Colo.App.2002) (same); see also Todd, 980 P.2d at 979 ("[Slection (c) of Rule 87 requires that trial courts sanction all failures to disclose under Rules 26(a) and 26(e) with evidence or witness preclusion unless the failure to disclose is either substantially justified or harmless.") (emphasis added). Not even Trattler proposes the interpretation adopted by the majority, instead arguing that the nondisclo-sures were harmless.
The majority appears to be concerned that in this particular case, expert witness preclusion was too harsh a sanction for Trattler's failure to disclose her experts' testimonial histories. For example, it suggests that testimonial history is "not central to the case" because it will only be used by the defendants for impeachment purposes; that Tratt-ler's expert reports were complete except for the testimonial histories; that the defendants could access the experts' testimonial histories in a computer database; that the defendants could have deposed the experts a second time; and that Trattler was not to blame for her experts' nondisclosures. Maj. op. at 682. From this, the majority concludes that the trial court's sanction of "precluding Trattler's experts from testifying was disproportionate to the failure to disclose testimonial history." Id.
Yet Rule 87(c)(1) permits the trial court to weigh all of these considerations. As noted above, while the first sentence of the rule states that the nondisclosing party "shall" not be permitted to present evidence, the second sentence provides that "[in addition to or in lieu of this sanction [of expert witness preclusion], the court, on motion after affording an opportunity to be heard, may impose other appropriate sanctions ...." In my view, the trial court is in the best position to consider whether a sanction other than expert witness preclusion is appropriate given the circumstances of the case. The majority, however, through its mistaken interpretation of Rule 37(c)(1), declares expert witness preclusion to be out of bounds from the beginning, and then weighs for itself whether the trial court's sanction of "precluding Trattler's experts from testifying was disproportionate to the failure to disclose testimonial history," concluding that it was. Maj. op. at 682.
Contrary to the majority's conclusion, see id. at 681-82, I do not believe that the trial court in this case believed that expert witness preclusion was mandatory, nor could it, given that a motion for sanctions was made. Rather, it based its decision on the cireum-stances of this particular case, finding that other possible remedies such as additional depositions or continuing the trial were not appropriate. The trial court's findings of fact and the record before us indicate that Trattler's initial expert disclosures, due 120 days before trial but filed one week thereafter based on Trattler's request to postpone the deadline, provided no testimonial history for either Dr. Schapira or Dr. Birrer, despite the clear requirements of Rule 26(a)(2)(B)(D). After the defendants requested the experts' testimonial history, Trattler provided a partial list for each doctor on May 20, 2004, ninety days before trial. Dr. Schapira's list contained only thirty-five cases, twenty-two of which were not fully identified. This list was supplemented twice prior to Dr. Schapi-ra's June 15, 2004 deposition. At that deposition, Dr. Schapira listed additional cases from memory but was nonetheless unable to state that his listing was complete. On July 2, 2004, defendants filed motions to strike Dr. Schapira and Dr. Birrer for failure to disclose their testimonial histories. On July 9, 2004, only forty-five days before trial, Tratt-ler filed what she claimed to be a complete list of Dr. Schapira's prior testimony, identifying 117 additional cases. Even that listing did not contain all of the information required by Rule 26(a)(2)(B)(I). Further, even after this "final" list was filed, defendants *686discovered an additional fifteen cases in which Dr. Schapira had testified.
Dr. Birrer's list filed on May 20, 2004, ninety days before trial, contained only six cases. His list was not supplemented before June 21, when defendants took his deposition. Dr. Birrer testified that his list was incomplete and that he had lost access to his administrative calendar when he left his previous job on May 29, 2004. He conceded that he did have access to his administrative calendar on April 30, 2004, when the initial expert disclosures were filed, and on May 20, 2004, when his incomplete list of cases was provided. Through their own efforts, defendants later located six additional cases in which Dr. Birrer had testified. Three weeks after the deposition, and only thirty-nine days before trial, Trattler filed a supplemental disclosure listing a total of fourteen cases. However, Dr. Birrer provided no certification that the list was complete and accurate-nor could he, given that he had lost access to his calendar, and that he could not recall his prior testimonial history.
It is thus unclear to this day whether complete testimonial histories for these experts were ever provided. Dr. Schapira's final testimonial history omitted fifteen cases discovered through the defendants' independent research. Further, Dr. Birrer would never be able to certify a complete and aceu-rate testimonial history, because he did not provide a full list during the time that he had access to his administrative calendar and because he was unable to reconstruct a complete list of cases from memory.
In my view, the trial court was acting within its discretion when it found that these nondisclosures warranted preclusion of the expert witnesses' testimony. The trial court found that based on "[the sheer volume of the testimony Dr. Schapira failed to disclose"-including over a hundred cases that were disclosed after the disclosure deadline-his conduct was "either willful or grossly negligent." The trial court concluded that the nondisclosure was not harmless, in that most of Dr. Schapira's cases were not disclosed until after his deposition, and that the offer of a second deposition only a few weeks before trial was an insufficient remedy. As for Dr. Birrer, the trial court concluded that "[dliscloging only half the cases where a witness has given deposition or trial testimony is not substantial compliance, and the lack of disclosure is not harmless" for the same reasons provided with regard to Dr. Schapira, and because Dr. Birrer was unable to certify that his list was complete. In addition, the court made an implicit finding of willfulness or gross negligence on the part of Dr. Birrer, stating:
[He] attempted to excuse his failure to produce a complete list by claiming that he did not have access to his administrative calendar due to a change in employment. However, he was still at the employment where his administrative calendar was located on computer [sic] at the time of the original [disclosure] and the first supplemental disclosure.
The purposes of the Rule 26 requirements are "to enable opposing counsel to obtain prior testimony of the expert that may be relevant to the proposed testimony in the pending case and to enable a party to prepare for eross-examination at a deposition or a trial." Svendsen, 94 P.3d at 1207; Carlson, 58 P.3d at 1059. In particular, an expert's prior testimony can provide impeachment evidence, as well as information relevant to the expert's credibility and possible bias. Rule 26(a) is designed to prevent the discovering party from having to expend substantial time and resources to discover necessary information. See, eg., Svendsen, 94 P.3d at 1207; see also Todd, 980 P.2d at 979 (stating that the purpose of Rule 87(c)(1) is to "reduce abuses of the system such as dilatory discovery tactics and inefficient trial preparation"). In this case, the defendants were able to uncover some, but not all, of the experts' prior testimony. The trial court was well within its discretion to preclude the experts, rather than requiring the defendants to expend additional time and money to investigate the experts' prior case history and take additional depositions concerning over a hundred undisclosed cases shortly before trial.
IL.
For the foregoing reasons, I would find that expert witness preclusion was an avail*687able sanction to the trial court, and that the court did not abuse its discretion in ordering such preclusion given the cireumstances of the case. I therefore respectfully dissent from the majority's opinion.