New Mexico Expert Witness Rules: What Litigators Need to Know

New Mexico civil litigation depends heavily on expert witness testimony, especially in medical malpractice, product liability, and other technically complex cases. The state’s procedural framework aligns closely with federal civil procedure and evidentiary standards, with a strong emphasis on early disclosure and methodological rigor. Attorneys litigating in New Mexico must comply with detailed rules governing expert discovery, fees, and admissibility to avoid sanctions, exclusion, or trial delays.

Designation Requirements

New Mexico does not require a formal motion to designate expert witnesses. Instead, expert identification occurs through disclosures under Rule 1-026 NMRA (the New Mexico Rules of Civil Procedure for District Courts), which closely parallels Federal Rule 26.

When a party intends to call an expert at trial, they must disclose:

• The identity of the expert
• The subject matter of the expected testimony
• A summary of facts and opinions
• The basis and reasons for each opinion
• The expert’s qualifications and compensation

Failure to timely disclose expert information may result in preclusion under Rule 1-037 NMRA, particularly when the nondisclosure is deemed unjustified or prejudicial.

Expert Disclosure Process

Under Rule 1-026(B)(6) NMRA, parties must disclose the following regarding any testifying expert:

• A written report if ordered by the court or required under a scheduling order
• The expert’s credentials
• The opinions to be expressed
• The data or information considered in forming opinions
• Exhibits to be used
• The expert’s publication list (past 10 years)
• Cases testified in (past 4 years)
• Compensation terms

Although expert reports are not required by default, they are often ordered in complex civil cases, particularly where multiple experts are expected or highly technical subject matter is involved.

Courts typically impose disclosure deadlines via scheduling orders that define:

• Plaintiff’s expert deadlines
• Defendant’s expert deadlines
• Rebuttal expert deadlines
• Discovery and motion cutoffs

Required Declarations

New Mexico does not require expert affidavits or declarations as part of routine expert disclosure. However, when filing or defending motions for summary judgment, expert declarations or affidavits are often essential to demonstrate a triable issue of fact.

Under Rule 1-056(E) NMRA, affidavits used to support or oppose summary judgment must:

• Be made on personal knowledge
• Set forth admissible facts
• Show that the declarant is competent to testify

In medical malpractice cases, New Mexico requires a qualified medical expert to support claims of breach of the standard of care and causation. Although no formal affidavit requirement exists at the pleading stage, expert opinion is required to survive summary judgment in almost all professional negligence matters.

Fees and Compensation

Expert witness compensation in New Mexico is not capped by statute and is generally determined by private agreement. However, when a party deposes the opposing party’s expert, Rule 1-026(B)(6)(c) NMRA requires the deposing party to pay:

• A reasonable fee for the expert’s time
• Compensation for time spent preparing and attending the deposition

Courts may resolve disputes over fee reasonableness, particularly if the fee is excessive or used to deter discovery.

Discovery Scope and Limitations

New Mexico permits robust expert discovery under Rule 1-026 NMRA. Permitted discovery includes:

• Reports, if required by court order
• The expert’s qualifications
• A list of prior testimony
• Materials considered, reviewed, or relied upon
• Compensation terms

While attorney-expert communications are generally protected by the work-product doctrine, this protection may be overridden when the communication contains facts or data the expert relied on. Additionally, the discovery of non-testifying consultants is not permitted unless the requesting party demonstrates exceptional circumstances.

Depositions of disclosed experts are permitted and typically occur after reports or summaries are exchanged.

Admissibility Standards

New Mexico follows the Daubert standard for admissibility of expert testimony, as adopted in State v. Alberico, 116 N.M. 156 (1993) and codified in Rule 11-702 NMRA.

To be admissible, expert testimony must:

1. Be offered by a qualified expert
2. Assist the trier of fact
3. Be based on sufficient facts or data
4. Be the product of reliable principles and methods
5. Be reliably applied to the facts of the case

Trial judges act as gatekeepers, responsible for ensuring that scientific and technical expert opinions meet thresholds of reliability and relevance. Courts may hold Daubert hearings before trial to assess whether an expert’s methodology is valid and appropriately applied.

Key Deadlines & Strategy Notes

Expert deadlines in New Mexico are controlled by the court’s scheduling order, which typically includes:

• Plaintiff’s expert disclosure: 90–120 days before trial
• Defendant’s expert disclosure: 30–60 days later
• Rebuttal expert disclosure: Often 30 days after the defendant’s disclosure
• Expert discovery cut-off: Typically 30–45 days before trial
• Daubert motions or motions to exclude: Filed per pretrial motion schedule

Failure to comply with deadlines or fully disclose expert opinions can result in exclusion under Rule 1-037 NMRA. Because New Mexico courts take the gatekeeping role seriously, experts must be thoroughly vetted and prepared to defend both their methodology and the foundation for their opinions.

State-Specific Statutes & Local Rules

• Rule 1-026(B)(6) NMRA: Governs expert disclosures
• Rule 1-037 NMRA: Sanctions for failure to disclose
• Rule 1-056(E) NMRA: Summary judgment affidavits
• Rule 11-702 NMRA: Admissibility of expert testimony
• State v. Alberico, 116 N.M. 156 (1993): Landmark Daubert case in New Mexico

Some judicial districts and trial courts in Bernalillo, Santa Fe, and Doña Ana counties may issue supplemental pretrial orders with detailed disclosure requirements or specific forms for expert identification. Practitioners must ensure compliance with local rules and standing orders.