Background
Jacqueline Harris died from an acute pulmonary embolism approximately 30 days after undergoing a total knee replacement performed by Dr. Jack Lennox at Beaumont Hospital in May 2019. Her estate alleged that Lennox committed malpractice by prescribing only aspirin rather than a prescription-strength anticoagulant. The complaint was filed in April 2021, supported by an affidavit of merit (AOM) signed by Dr. B. Sonny Bal, an orthopedic surgeon who attested he had been in active clinical practice during the year preceding the alleged malpractice. Plaintiff listed Bal as her sole orthopedic surgery expert.
Bal’s deposition was scheduled for August 15, 2022, but he cancelled due to an emergency. Plaintiff’s counsel was unable to reschedule and, on September 16, 2022, filed an amended witness list substituting Dr. John Hall without first obtaining court permission. The circuit court struck the amended list and ordered plaintiff to produce Bal for deposition by November 2, 2022. Defendants subsequently unearthed deposition transcripts and LinkedIn records showing Bal had retired from practicing and teaching medicine in November 2017—nearly two years before the surgery at issue—rendering the AOM potentially invalid under MCL 600.2912d. The circuit court denied plaintiff’s motion to amend her witness list and her motion for voluntary dismissal, then granted summary disposition in favor of defendants, finding the AOM defective and closing the case.
The Court of Appeals reversed, holding the circuit court abused its discretion by failing to evaluate all eight factors set forth in Dean v. Tucker, 182 Mich App 27 (1990), before effectively dismissing the action. Defendants sought leave to appeal, and the Michigan Supreme Court ordered oral argument on the applications.
The Court’s Holding
In a unanimous opinion by Justice Zahra, the Court held that the proper standard for evaluating a motion to amend a witness list is the “good cause” standard stated in MCR 2.401(I)(2)—not the eight-factor Dean test. The Dean factors were developed to guide courts imposing discovery sanctions that result in dismissal; they focus on party misconduct and non-compliance with discovery orders rather than on whether a party showed adequate diligence in securing an expert. Because MCR 2.401(I)(2) is unambiguous, courts should apply its plain language, with the central inquiry being the moving party’s diligence and the prejudice—if any—to either side from granting or denying the motion.
Nonetheless, the Court agreed with the Court of Appeals that the circuit court abused its discretion under the very good-cause standard it purported to apply. The record showed that plaintiff had been in regular contact with Bal, who had cooperated in scheduling, and that much of the post-August 2022 delay was attributable to defendants’ own scheduling constraints and their efforts to challenge Bal’s qualifications. The circuit court also erroneously believed discovery had closed in June 2022 when it had actually been extended by stipulation to December 12, 2022. Because plaintiff acted promptly to identify a replacement expert available within the extended discovery period, and because the court failed to articulate concrete prejudice tied to plaintiff’s lack of diligence, the denial of the motion to amend was an abuse of discretion. Summary disposition was therefore premature, having been predicated on that erroneous ruling.
The Court also noted in a footnote that, absent a finding of intentional misuse of the AOM process, dismissal should have been without prejudice under Kirkaldy v. Rim, 478 Mich 581 (2007), leaving plaintiff whatever limitations period remained to re-file with a conforming affidavit of merit.
Key Takeaways
- Michigan trial courts must apply the MCR 2.401(I)(2) “good cause” standard—not the Dean v. Tucker eight-factor test—when ruling on motions to amend a witness list to add or substitute an expert.
- Good cause analysis centers on the moving party’s diligence and actual prejudice to either side; a court must accurately assess the procedural record, including any extended discovery deadlines, before concluding a party acted without due diligence.
- Preclusion of an expert that effectively dismisses a case is subject to heightened scrutiny; summary disposition that flows directly from a flawed witness-list ruling is itself premature and reversible.
- Where a defective AOM is the basis for dismissal and no intentional misconduct is found, the correct remedy is dismissal without prejudice, not with prejudice.
Why It Matters
This decision clarifies a recurring point of confusion in Michigan civil practice: the Dean factors, widely cited in the Court of Appeals, are a discovery-sanctions framework and do not govern the distinct question of whether good cause supports amending a witness list. By anchoring the analysis squarely in MCR 2.401(I)(2), the Court gives trial judges clearer guidance and reduces the risk that a plaintiff’s malpractice claim will be extinguished by procedural mismatch between the standard applied and the relief sought.
For medical malpractice litigants specifically, the decision reinforces that courts must carefully examine the full timeline—including any stipulated discovery extensions—before penalizing a plaintiff for an expert’s sudden unavailability. Attorneys relying on a single expert witness whose deposition has yet to be taken should move promptly to substitute upon any sign of non-cooperation; but courts, in turn, must weigh that diligence fairly rather than conflating a witness’s last-minute withdrawal with a plaintiff’s failure to prosecute.