Good Cause Governs Expert-Witness Substitution Under MCR 2.401(I)(2); Dean v Tucker Factors Not Mandatory

I. Introduction

Case: SMITH v BEAUMONT HEALTH (Estate of Jacqueline Harris v Beaumont Health), Docket Nos. 167716 & 167720 (Mich, June 30, 2026).
Parties: Lawanna Smith, personal representative of the Estate of Jacqueline Harris (plaintiff) v Beaumont Health; Tri County Orthopedics, PC; and Jack D. Lennox, D.O. (defendants).
Context: A medical-malpractice action alleging Dr. Lennox failed to prescribe prescription-strength anticoagulation after knee replacement surgery, leading to Harris’s death from pulmonary embolism roughly 30 days later.

The dispute became procedurally decisive when plaintiff sought to replace her listed orthopedic expert (B. Sonny Bal, M.D., who signed the affidavit of merit) with a new expert (John Hall, M.D.) after Dr. Bal cancelled a scheduled deposition and then became difficult to reschedule. The circuit court struck plaintiff’s amended witness list (filed without leave), compelled Dr. Bal’s deposition, denied plaintiff’s later motion to amend the witness list and motion for voluntary dismissal, and then granted summary disposition after accepting defendants’ challenge to the affidavit of merit as invalid under MCL 600.2912d. The Court of Appeals reversed, holding the trial court was required to consider the multifactor framework from Dean v Tucker. The Michigan Supreme Court granted argument in lieu of leave to decide the governing standard for witness-list amendments and whether the trial court’s rulings could stand.

II. Summary of the Opinion

The Supreme Court unanimously held that the proper standard for allowing an untimely witness (including a substitute expert) is the “good cause” standard in MCR 2.401(I)(2), not mandatory consideration of the Dean v Tucker factors. The Court rejected the Court of Appeals’ rule that a trial court must march through every Dean factor when deciding a motion to amend a witness list.

Even so, the Supreme Court concluded the circuit court abused its discretion under the very good-cause standard it purported to apply because the record supported plaintiff’s diligence and undermined the court’s stated prejudice rationale (including the court’s mistaken belief that discovery had already closed). Because the denial of amendment left plaintiff without a viable expert, the ensuing summary disposition was deemed premature. The Court reversed in part and remanded.

The Court also noted (in a remedial footnote) that dismissal for a defective affidavit of merit is generally without prejudice absent findings of intentional misuse of the affidavit-of-merit requirement.

III. Analysis

A. Precedents Cited

1. The “Dean factors” and their proper domain: sanctions, not witness-list amendment standards

  • Dean v Tucker, 1 82 Mich App 27 (1 990)
    The Court recharacterized Dean as a sanctions case: it involved barring witnesses as a penalty for a discovery/witness-list violation that effectively ended the plaintiff’s case. The Dean factors (willfulness, history of noncompliance, prejudice, notice, deliberate delay, overall compliance, attempts to cure, and lesser sanctions) were developed to guide courts in choosing proportionate discovery sanctions—especially when the functional result is dismissal.
  • Duray Dev, LLC v Perrin, 288 Mich App 143 (2010)
    Cited as a source that also describes the Dean factors (often referred to as the “Dean/Duray factors”). The Supreme Court’s point was not to dispute their relevance to sanctions but to limit their mandatory use outside that context.
  • Kalamazoo Oil Co v Boerman, 242 Mich App 75 (2000)
    Used to reinforce that discovery sanctions are inherently discretionary and should be proportionate and just; this supports why multifactor sanction frameworks exist but does not transform them into the governing test for “good cause” under MCR 2.401(I)(2).
  • The Court of Appeals’ reliance on dismissal-avoidance and sanction caselaw—e.g., Tolas Oil & Gas Exploration Co v Bach Servs & Mfg, LLC, 347 Mich App 280 (2023), Gueye v State Farm Mut Auto Ins Co, 343 Mich App 473 (2022), and Vicencio v Jaime Ramirez, MD, PC, 211 Mich App 501 (1995)—is treated as misdirected insofar as it substitutes sanction doctrine for the rule-based “good cause” standard governing late-listed witnesses.

2. “Good cause” under MCR 2.401(I)(2): the Court roots the test in rule text and witness-substitution caselaw

  • Tisbury v Armstrong, 194 Mich App 19 (1991)
    Presented as the most apt exemplar of “good cause” analysis: adequate explanation for witness unavailability, minimal prejudice where the original expert had not been deposed, limited effect on mediation/case evaluation, and no repeated delays. The Supreme Court draws from this the modernized core considerations of diligence and prejudice.
  • Levinson v Sklar, 181 Mich App 693 (1989)
    Another substitution case: where the original expert had not been deposed and mediation was not necessarily undermined, striking the replacement expert and dismissing was reversed. This reinforces that prejudice is contextual and often tied to avoidable expense or surprise—not simply “late stage” labeling.
  • Cox v Hartman, 322 Mich App 292 (2017)
    Serves as the counterexample: the plaintiff waited until after summary disposition to move to add a new expert despite earlier notice of qualifications problems. The Supreme Court uses Cox to illustrate when lack of diligence defeats good cause—contrasting sharply with plaintiff’s record of active scheduling efforts here.
  • The Court also references unpublished decisions—Howard-Reed v Braver, Pawlowski v Kosar, Morris v St Clair Orthopaedics & Sports Med, PC, Witt v Glazer—to show recurring diligence themes: earlier notice of a problem, discovery closure, deposition timing, and strategic delay can defeat “good cause.”

3. Interpretation framework and summary-disposition standards

  • Hairston v LKU, CAM Constr v Lake Edgewood Condo Ass'n, and Carter v DTN Mgt Co
    These cases supply the interpretive lens: court-rule interpretation is reviewed de novo, and de novo means no deference to lower courts’ legal interpretations.
  • Beals v Michigan and Brown v Brown
    Provide the de novo review standard for summary disposition and the MCR 2.116(C)(10) requirement to view evidence in the light most favorable to the nonmoving party.
  • People v Scott
    Supplies the abuse-of-discretion articulation: an outcome outside the “principled range of outcomes.”
  • Pena v Ingham County Road Com'n, 255 Mich App 299 (2003)
    Quoted by the circuit court for the “put up or shut up” stage after discovery closes. The Supreme Court’s analysis undermines the circuit court’s use of this premise because the circuit court incorrectly believed discovery had closed when it had been extended.

4. Affidavit-of-merit remedy and dismissal consequences

  • Kirkaldy v Rim, 478 Mich 581 (2007)
    Cited to clarify the baseline remedy for a defective AOM: dismissal without prejudice, leaving whatever limitations period remains.
  • Ottgen v Katranji, 511 Mich 223 (2023)
    Recognizes an exception: where a plaintiff intentionally violates MCL 600.2912d to gain time or improperly delay, dismissal with prejudice may be appropriate. The Supreme Court noted the circuit court made no finding of intentional misuse here.

5. What “good cause” means

  • People v Buie, 491 Mich 294 (2012) and Thomas M Cooley Law Sch v Doe 1, 300 Mich App 245 (2013)
    Provide the definition used by the Court: good cause is a “satisfactory, sound or valid reason.”

6. The sanction-factor cases underlying Dean (and why they do not fit the witness-amendment question)

The Court catalogued the older sanction authorities that informed Dean—including MacArthur Patton Christian Ass'n v Farm Bureau Ins Group, Houston v Southwest Detroit Hosp, Daugherty v Michigan (After Second Remand), Bellok v Koths, Middleton v Margulis, Edge v Ramos, North v Dep't of Mental Health, and Pollum v Borman's, Inc. The Court’s throughline is that these cases center on misconduct and discovery-order violation management, whereas witness substitution under MCR 2.401(I)(2) turns chiefly on diligence and litigation prejudice—not punishment.

B. Legal Reasoning

1. The rule-text holding: MCR 2.401(I)(2) supplies the governing standard

The Supreme Court treated the witness-list question as a straightforward rule-interpretation problem. MCR 2.401(I)(2) expressly states that an unlisted witness may be prohibited “except upon good cause shown.” Because the rule is “stated in plain terms,” the Court found “no basis to depart from the plain language.” The decision thus establishes a clear hierarchy: when the court rule speaks directly, common-law factor tests designed for other contexts should not be imported as mandatory criteria.

2. What “good cause” requires in this setting: diligence and prejudice as the primary considerations

Distilling the substitution precedents (Tisbury, Levinson, Cox), the Court announced that while Dean-type considerations may sometimes be relevant, they are not the standard. Instead, trial courts should focus primarily on:

  1. The moving party’s diligence in securing the witness (including how quickly the party moved once a problem was discovered and whether the party had notice earlier); and
  2. Prejudice to either side from granting or denying the motion (with an emphasis on prejudice tied to avoidable expense, discovery disruption, surprise theories, and case evaluation impacts).

This framing narrows the inquiry to what MCR 2.401(I)(2) is designed to manage: the orderly, fair presentation of witnesses—not retrospective discipline for litigation misconduct.

3. Application to the record: why the circuit court abused discretion

  • Diligence was supported by the scheduling record. Plaintiff maintained contact with Dr. Bal, proposed deposition dates as early as June 2022, and the parties agreed on August 15, 2022 largely due to defense-side availability. Dr. Bal then cancelled due to an emergency. The Court found the circuit court’s suggestion that plaintiff should have discovered uncooperativeness “much sooner” ignored this record of cooperation up to the cancellation.
  • Delay attribution was flawed. The Court observed that September–October activity was driven in significant part by defendants’ efforts to establish that Dr. Bal’s AOM was invalid—complicating the circuit court’s premise that plaintiff alone caused the critical delay.
  • Prejudice analysis rested on a factual mistake. The circuit court stated discovery had closed June 7, 2022, but discovery had been extended by stipulated order to December 12, 2022. The Supreme Court treated this mistake as central because “late stage” prejudice often depends on whether discovery can still accommodate the substitution without undue burden.
  • Summary disposition was “premature” because it was downstream of the erroneous witness ruling. By denying amendment, the court left plaintiff without the expert testimony needed to establish standard of care and breach, which functionally set up dismissal. The Supreme Court held that the summary-disposition ruling could not stand when it was predicated on an abuse of discretion in denying the substitution.

C. Impact

1. A clarified statewide standard for witness-list amendments

The decision establishes a clear procedural rule for Michigan trial courts: motions to amend witness lists are governed by the “good cause” standard of MCR 2.401(I)(2), and courts are not required to apply the Dean v Tucker sanctions factors as a checklist. This should reduce inconsistent motion practice in medical malpractice litigation (where expert substitutions are common) and in civil litigation generally.

2. Recalibration of the “dismissal-like” effect without collapsing the inquiry into sanction doctrine

The Court acknowledged that denying an expert substitution can be outcome-determinative, but it did not accept that this automatically triggers the Dean sanctions framework. Instead, the “dismissal-like” consequence becomes part of the good-cause context—especially when assessing prejudice to the moving party and the policy favoring merits adjudication—without converting every substitution motion into a sanctions hearing.

3. Practical effects on litigation behavior

  • Earlier, better-developed diligence records. Parties seeking substitution will likely document efforts to schedule depositions, preserve communications, and move promptly once unavailability or qualification issues arise.
  • More disciplined prejudice arguments. Opponents will be incentivized to show concrete prejudice (duplicative expert costs, completed depositions, looming trial/case evaluation disruption, surprise theories), rather than relying on generalized assertions of “late stage.”
  • Trial courts must be precise about scheduling orders. The Court’s reliance on the discovery-extension mistake signals that inaccurate docket assumptions can turn discretionary rulings into reversible error.

IV. Complex Concepts Simplified

  • Affidavit of Merit (AOM) (MCL 600.2912d): A document required at the start of a Michigan medical-malpractice case, signed by a qualified health professional, attesting that the case has medical support regarding standard of care, breach, and causation.
  • Witness list (MCR 2.401(I)): The court-ordered list of people (including experts) a party intends to call at trial. Late-added witnesses risk being excluded unless “good cause” is shown.
  • “Good cause” (MCR 2.401(I)(2)): A satisfactory, sound, or valid reason for the late witness—commonly evaluated through diligence (did you act promptly and reasonably?) and prejudice (does the change unfairly burden the opponent or derail the schedule?).
  • Summary disposition (MCR 2.116(C)(10)): Michigan’s mechanism to end a case when there is no genuine dispute of material fact and the moving party is entitled to judgment as a matter of law—often after discovery.
  • Discovery sanctions vs. scheduling enforcement: Sanctions punish litigation misconduct (where Dean factors fit). Witness-list amendments manage case administration (where MCR 2.401(I)(2)’s “good cause” governs).

V. Conclusion

SMITH v BEAUMONT HEALTH draws a firm doctrinal line: the test for amending a witness list is “good cause” under MCR 2.401(I)(2), not mandatory application of the Dean v Tucker sanction factors. The Court simultaneously reinforced that “good cause” is not toothless—trial courts must meaningfully assess diligence and prejudice based on the actual scheduling record. On these facts, where plaintiff actively attempted to schedule the original expert, promptly sought a replacement, and discovery remained open (contrary to the circuit court’s belief), the denial of substitution fell outside the principled range of outcomes and rendered summary disposition premature. The decision should steer future Michigan courts toward rule-text fidelity and a more focused, record-driven assessment of expert substitutions.