Colorado Expert Witness Rules: What Litigators Need to Know

Colorado applies a detailed and rule-driven framework to expert witnesses in civil litigation, closely modeled after the federal rules but with specific state-level procedural nuances. Attorneys must be meticulous in complying with disclosure deadlines, report formatting, and admissibility standards, especially given the courts’ proactive gatekeeping role under Colorado’s version of Rule 702. In high-stakes cases—from personal injury to professional malpractice—expert compliance is not merely procedural but outcome-determinative.

Designation Requirements

In Colorado state courts, expert witnesses are designated through the formal disclosure process outlined in Colorado Rules of Civil Procedure (C.R.C.P.) 26(a)(2). This rule differentiates between two types of experts:

1. Retained Experts (those hired for litigation)
2. Non-Retained Experts (e.g., treating physicians)

For retained experts, the disclosing party must file a comprehensive written report. For non-retained experts, only a summary of expected testimony is required, but it must be specific enough to inform opposing counsel of the opinions to be offered at trial.

• The designation process requires that parties disclose:
• The name and contact information of the expert
• The subject matter of testimony
• A summary of opinions
• The qualifications of the expert
• Materials relied upon in forming opinions
• Compensation terms

Failure to properly designate an expert or provide the required materials can result in exclusion under Rule 37(c)(1).

Expert Disclosure Process

Under C.R.C.P. 26(a)(2)(B), parties must serve detailed expert reports for retained experts. These reports must include:

• A complete statement of all opinions
• The basis and reasons for each opinion
• Supporting data or information
• Exhibits to be used
• Qualifications and publications (past 10 years)
• Prior testimony (past 4 years)
• Compensation arrangements

Disclosures must occur no later than 126 days before trial, unless modified by a case management order (CMO). Rebuttal expert disclosures are due 91 days before trial, and supplemental disclosures (if any) must be served promptly as new information becomes available.

Reports must be signed by the expert and are subject to the same standards of admissibility as in-court testimony. Courts will not hesitate to exclude experts whose disclosures are insufficient or untimely.

Required Declarations

While Colorado does not require expert declarations in the ordinary course of disclosure, they become essential during summary judgment or pretrial motions. Under C.R.C.P. 56(e), affidavits or declarations submitted in support of or in opposition to summary judgment must:

• Be made on personal knowledge
• Set forth facts admissible in evidence
• Affirm the expert’s competence to testify

In medical malpractice actions, a signed certificate of review is required under C.R.S. § 13-20-602. This affidavit, submitted within 60 days of filing the complaint, must affirm that the plaintiff has consulted a qualified expert who believes the claim has merit. Failure to comply leads to mandatory dismissal.

Fees and Compensation

Expert fees in Colorado are not regulated by statute but must be reasonable. Compensation for time spent preparing and testifying is usually governed by agreement. When one party seeks to depose another’s expert, C.R.C.P. 26(b)(4)(E) entitles the expert to reasonable compensation.

Courts may intervene if the fee is excessive or if the expert refuses to appear without unjustified demands. Compensation for preparation time may also be ordered, particularly for complex testimony.

Discovery Scope and Limitations

Colorado allows extensive expert discovery, particularly for retained experts. Under C.R.C.P. 26(b)(4):

• Experts must produce all data, notes, and literature relied upon
• Opposing parties may take depositions of disclosed experts
• The expert’s methodology and analysis are subject to scrutiny

Draft reports and communications between counsel and experts are not protected under Colorado law unless shielded by privilege or the attorney work-product doctrine. This is a key distinction from federal practice post-2010 amendments to FRCP 26. As a result, all drafts and emails exchanged with the expert may be discoverable unless clearly protected.

Non-testifying consultants, on the other hand, remain shielded from discovery unless the opposing party can demonstrate exceptional circumstances making disclosure necessary.

Admissibility Standards

Colorado formally adopted the Daubert standard in People v. Shreck, 22 P.3d 68 (Colo. 2001) and codified it in CRE 702. This rule requires that expert testimony be:

1. Based on scientific, technical, or other specialized knowledge
2. Helpful to the trier of fact
3. Rooted in reliable principles and methods
4. Applied reliably to the facts of the case

Trial courts serve as gatekeepers, responsible for ensuring that expert testimony is both relevant and reliable. Courts may conduct Shreck hearings—analogous to Daubert hearings—to assess admissibility before trial. The factors considered include:

• General acceptance within the relevant scientific community
• Peer review and publication
• Testability of the method
• Known or potential error rate
• Maintenance of standards

Expert testimony failing to meet these benchmarks is subject to exclusion, regardless of the expert’s credentials.

Key Deadlines & Strategy Notes

Key expert-related deadlines under Colorado rules include:

• Initial expert disclosures: 126 days before trial
• Rebuttal disclosures: 91 days before trial
• Certificate of review (med-mal cases): 60 days from filing the complaint
• Pretrial motions to exclude experts: Deadline set by trial court or case management order

Strategically, practitioners should ensure early engagement and vetting of experts to meet Colorado’s rigorous report and reliability standards. Experts must be prepared for deposition, and their methodologies must be defensible under Daubert scrutiny. Waiting until summary judgment to test an expert’s qualifications is risky given Colorado’s strong emphasis on pretrial admissibility hearings.

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
• People v. Shreck, 22 P.3d 68 (Colo. 2001): Colorado’s foundational expert admissibility case

In addition to state-level rules, judicial districts in Denver, Boulder, and Jefferson counties may issue differentiated case management plans (DCMPs) that adjust disclosure schedules and discovery procedures. Attorneys should consult the trial court’s case management order for jurisdiction-specific requirements.