Expert Witnesses in Colorado
In Colorado, a witness is an expert if they offer opinion testimony based on specialized knowledge that would assist the trier of fact.
Rules Governing Disclosure
Colorado courts enforce C.R.C.P. 26(a)(2) strictly, especially where opinions go to liability, causation, or damages. Colorado distinguishes between retained and non-retained experts.
A. Retained testifying experts – Rule 26(a)(2)(B)
For experts retained or specially employed to provide expert testimony, the party must disclose a written expert report. The report must be prepared and signed by the expert and must contain:
(a) a complete statement of all opinions to be expressed and the basis and reasons therefor;
(b) a list of the data or other information considered by the witness in forming the opinions;
(c) references to literature that may be used during the witness’s testimony;
(d) copies of any exhibits to be used as a summary of or support for the opinions;
(e) the qualifications of the witness, including a list of all publications authored by the witness within the preceding ten years;
(f) the fee agreement or schedule for the study, preparation and testimony;
(g) an itemization of the fees incurred and the time spent on the case, which shall be supplemented 14 days prior to the first day of trial; and
(h) 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
B. Non-retained experts – Rule 26(a)(2)(C)
For experts not retained for litigation (e.g., treating physicians, investigating professionals), a full report is not required, but disclosure is still mandatory.
The disclosure must include:
(a) a complete description of all opinions to be expressed and the basis and reasons therefore;
(b) a list of the qualifications of the witness; and
(c) copies of any exhibits to be used as a summary of or support for the opinions. If the report has been prepared by the witness, it shall be signed by the witness.
Failure to properly designate an expert or provide the required materials can result in exclusion under Rule 37(c)(1).
Required Declarations
Although Colorado’s disclosure rules do not generally require expert declarations, such statements often become critical at the summary judgment or pretrial motion stage. Pursuant to C.R.C.P. 56(e), affidavits or declarations offered in support of or in opposition to summary judgment must be based on personal knowledge, present facts that would be admissible at trial, and establish the expert’s qualifications to testify. In medical malpractice cases, Colorado law further requires a signed certificate of review under C.R.S. § 13-20-602, which must be filed within sixty days of the complaint and confirm that a qualified expert has been consulted and supports the claim’s merit. Noncompliance with this requirement mandates dismissal of the action.
Admissibility Standards
In Colorado, expert testimony is admitted under a Daubert-based reliability standard, but with some Colorado-specific phrasing and emphasis. The controlling authority is Colorado Rule of Evidence (CRE) 702, as interpreted by the Colorado Supreme Court.
The focus is on methodology, not conclusions. Colorado courts require trial judges to act as gatekeepers and evaluate whether the expert’s opinions are reasonably reliable, not whether they are correct.
Courts may consider (as applicable):
Whether the theory or technique can be and has been tested
Whether it has been peer reviewed
The known or potential error rate
The existence of standards controlling the technique
Whether the methodology is generally accepted in the relevant field
Attorney–Expert Communication Protection
Once an expert is designated to testify, transparency generally outweighs work-product protection. When an expert is designated as a testifying expert, Colorado courts hold that materials shared with the expert and considered in forming opinions are discoverable and this includes many materials that would otherwise qualify as attorney work product.
Key Deadlines & Strategy Notes
Initial expert disclosures: 126 days before trial
Rebuttal expert disclosures: 91 days before trial
Expert depositions: After disclosures, before discovery cutoff
Daubert motions: As set by Case Management Orders
From a strategic standpoint, counsel should involve and evaluate experts early to ensure compliance with Colorado’s demanding disclosure and reliability requirements. Experts should be thoroughly prepared for deposition, with methodologies that can withstand Daubert-based challenges. Delaying scrutiny of an expert’s qualifications until the summary judgment stage is a gamble, particularly in light of Colorado courts’ preference for resolving admissibility issues through pretrial proceedings.
Compensation
For any retained expert who will testify, Rule 26(a)(2)(B) requires disclosure of the compensation to be paid for the study and testimony in the case. The nature of compensation is fair game for discovery and cross-examination. Colorado courts are particularly sensitive to compensation structures that suggest improper influence.
State-Specific Statutes & Local Rules
• C.R.C.P. 26(a)(2): Governs expert disclosure and report requirements
• C.R.C.P. 56(e): Controls expert affidavits at summary judgment
• C.R.C.P. 26(b)(4): Provides for expert discovery and compensation
• C.R.S. § 13-20-602: Certificate of review requirement for professional negligence cases
• CRE 702: Governs admissibility of expert testimony
