Maine Expert Witness Rules: What Litigators Need to Know

Expert witnesses are integral to civil litigation in Maine, especially in cases involving medical malpractice, product liability, and professional negligence. Maine follows a procedure-driven system for expert disclosures, largely aligned with federal practices but with notable state-specific requirements. Expert testimony is subject to rigorous admissibility standards, and courts act as gatekeepers to ensure opinions are based on sound methodology and relevant to the case at hand. Counsel must strictly adhere to procedural rules under the Maine Rules of Civil Procedure (Me. R. Civ. P.) and Maine Rules of Evidence (M.R. Evid.) to avoid sanctions or exclusion.

Designation Requirements

Maine does not require a separate motion to designate expert witnesses. Instead, expert disclosure is governed by Me. R. Civ. P. 26(b)(4) and enforced through pretrial scheduling orders.

Each party must disclose:

• The identity of each expert expected to testify at trial
• The subject matter on which the expert will testify
• The substance of the facts and opinions
• The grounds for each opinion

Failure to properly and timely disclose an expert may lead to exclusion under Me. R. Civ. P. 37, particularly where late disclosure results in unfair surprise or prejudice to the opposing party. Courts strictly enforce disclosure timelines, which are often case-specific.

Expert Disclosure Process

Expert exchange in Maine is controlled by Rule 26(b)(4) and elaborated through court-ordered scheduling orders, which typically set staggered deadlines for the exchange of:

• Opening expert disclosures
• Rebuttal or responsive disclosures
• Expert depositions and challenges

The party disclosing the expert must provide:

• A summary of opinions
• The basis and reasoning for each opinion
• All documents, data, or publications relied upon
• The expert’s qualifications, including prior testimony
• The fee arrangement

While Maine does not require full expert reports in every case, written reports are often ordered by the court, particularly in complex or technical litigation. The practice of exchanging reports helps streamline discovery and minimize disputes about the scope of expert testimony at trial.

Required Declarations

Expert declarations or affidavits are not required as part of the disclosure process in Maine, but they are critical in motion practice, especially at the summary judgment stage under Me. R. Civ. P. 56(e).

An expert affidavit must:

• Be made on personal knowledge
• Contain facts admissible in evidence
• Show affirmatively that the affiant is competent to testify

In medical malpractice cases, Maine does not impose a statutory affidavit of merit requirement. However, expert testimony is generally required to establish a breach of the standard of care and causation. Absent such testimony, the case may not survive summary judgment.

Fees and Compensation

Expert witness compensation in Maine is governed by reasonableness and standard market practices. The party deposing a testifying expert must pay the expert a reasonable fee for time spent in deposition, under Me. R. Civ. P. 26(b)(4)(C).

While there are no statutory caps on expert fees, courts may intervene if a dispute arises over excessive billing. Factors considered include:

• The expert’s experience and credentials
• The complexity of the issues
• Customary rates within the field

Consulting experts—those retained but not expected to testify—are not subject to this rule, and their compensation remains confidential unless exceptional circumstances justify discovery.

Discovery Scope and Limitations

Discovery of expert opinions in Maine is regulated by Rule 26(b)(4) and includes:

• Testifying experts: Full discovery is allowed, including the subject matter, facts, opinions, and basis of those opinions.
• Consulting experts: Protected from discovery unless the requesting party demonstrates exceptional circumstances.
• Documents and data: All materials considered by the expert in forming their opinion must be disclosed.
• Drafts and communications: May be protected under the work-product doctrine, though this protection can be waived or overridden by court order in some situations.

Expert depositions are permissible once written disclosures are completed, and attorneys should be prepared to defend or challenge methodology during deposition if admissibility is likely to be contested.

Admissibility Standards

Maine follows a Daubert-style admissibility standard, codified in M.R. Evid. 702 and applied consistently through state case law, including Searles v. Fleetwood Homes of Pennsylvania, Inc., 878 A.2d 509 (Me. 2005).

Under Rule 702, expert testimony must be:

1. Offered by a qualified expert based on education, training, or experience
2. Relevant to assist the trier of fact
3. Based on sufficient facts or data
4. The product of reliable principles and methods
5. Reliably applied to the facts of the case

Trial judges serve as gatekeepers and may conduct Daubert hearings to evaluate whether the expert’s methodology meets the standard for admissibility. Mere credentials are not enough—the expert must demonstrate a scientific or technical basis for their conclusions.

Key Deadlines & Strategy Notes

Expert deadlines in Maine are typically set through the court’s scheduling order, which functions as the procedural backbone for all discovery and pretrial activity. A common timeline includes:

• Plaintiff’s expert disclosures: 90–120 days before trial
• Defense disclosures: 30–60 days after plaintiff’s
• Rebuttal disclosures: Often 30 days prior to close of discovery
• Motions to exclude (Daubert): Must be filed by the pretrial motion deadline

Strategically, experts should be retained early and integrated into case theory development. Because Maine courts scrutinize expert opinions for methodological rigor, experts must be prepared to defend their opinions under Daubert, both at deposition and through possible evidentiary hearings.

State-Specific Statutes & Local Rules

• Me. R. Civ. P. 26(b)(4): Governs expert discovery and disclosure procedures
• Me. R. Civ. P. 56(e): Requirements for affidavits supporting or opposing summary judgment
• Me. R. Evid. 702: Admissibility standard for expert testimony
• Searles v. Fleetwood Homes of Pennsylvania, Inc., 878 A.2d 509 (Me. 2005): Leading Daubert case in Maine

Attorneys should also review local court orders or pretrial scheduling notices, particularly in counties like Cumberland, York, and Penobscot, where individual judges may impose specific formatting requirements or expert report expectations.