Michigan medical malpractice: the affidavit of merit, and the 63 days to challenge it
Michigan procedure · Last verified August 17, 2026
Michigan front-loads medical malpractice. Before the case is really under way, both sides have filed sworn statements about the merits, and the window for attacking the other side's has already started running. MCR 2.112(L) is the court rule that sets those windows, and it is unusually unforgiving: a challenge made late is waived unless the court finds good cause.
The substantive requirements — what the affidavit must contain, who may sign it, how long the pre-suit notice period runs — live in the Public Health Code and the Revised Judicature Act, which this site does not carry. What follows is the procedural half, which is where the deadlines are.
Who must file, and what must be served
MCR 2.112(L)(1):
In an action alleging medical malpractice filed on or after October 1, 1993, each party must file an affidavit as provided in MCL 600.2912d and 600.2912e. Notice of filing the affidavit must be promptly served on the opposing party. If the opposing party has appeared in the action, the notice may be served in the manner provided by MCR 2.107. If the opposing party has not appeared, the notice must be served in the manner provided by MCR 2.105. Proof of service of the notice must be promptly filed with the court.
Three obligations, and the second is the one most often overlooked.
Each party files. Not just the plaintiff. MCL 600.2912d requires an affidavit of merit with the complaint; MCL 600.2912e requires an affidavit of meritorious defense from the defendant. The court rule treats them symmetrically.
Notice of filing must be served promptly, and the manner depends on whether the other side has appeared — ordinary service under MCR 2.107 if it has, service like a summons under MCR 2.105 if it has not.
Proof of service must be filed. This is a separate step from serving, and it is expressly required.
The two challenge deadlines
MCR 2.112(L)(2) is the heart of the rule:
In a medical malpractice action, unless the court allows a later challenge for good cause: (a) all challenges to a notice of intent to sue must be made by motion, filed pursuant to MCR 2.119, at the time the defendant files its first response to the complaint, whether by answer or motion, and (b) all challenges to an affidavit of merit or affidavit of meritorious defense, including challenges to the qualifications of the signer, must be made by motion, filed pursuant to MCR 2.119, within 63 days of service of the affidavit on the opposing party.
Two different triggers, and they are easy to confuse.
Notice of intent — with your first response. Not within some number of days of the notice; at the moment the defendant first responds to the complaint, "whether by answer or motion." A defendant that answers and then thinks about the notice of intent has already missed it.
Affidavit — 63 days from service. That includes "challenges to the qualifications of the signer," which is the most common ground of attack and the one that most often surfaces late, after the expert's specialty turns out not to match.
Both must be by motion under MCR 2.119, the general motion rule. Raising the point in a brief on something else is not a challenge under this rule.
The escape is narrow and judicial: "unless the court allows a later challenge for good cause." It is not a party's to give itself.
Amendment
The subsection closes with a saving provision:
An affidavit of merit or meritorious defense may be amended in accordance with the terms and conditions set forth in MCR 2.118 and MCL 600.2301.
MCR 2.118 is Michigan's general amendment rule — the same standard that governs amending a pleading. So a defective affidavit is not automatically fatal; it is amendable on the ordinary terms, which is why the challenging party's deadline matters so much. A challenge raised inside 63 days puts the defect in front of the court while amendment is still a live option for the other side; a challenge raised much later arrives after the case has been built on the affidavit.
Where this sits among Michigan's other malpractice rules
MCR 2.112(L) is a subdivision of the general rule on pleading special matters — the same rule that governs pleading capacity, fraud, conditions precedent, actions on insurance policies and written instruments. That placement is a useful reminder: the affidavit is treated as a pleading requirement, not as evidence.
Michigan also renames the dispositive motions other states call a motion to dismiss and summary judgment, combining them as summary disposition under MCR 2.116 — covered separately in Michigan summary disposition. A challenge to an affidavit under 2.112(L) is a different device with its own deadline, and filing one does not substitute for the other.
How Michigan compares to the federal rules
| Michigan | Federal | |
|---|---|---|
| Affidavit required in malpractice cases | yes, from each party | no counterpart |
| Where the requirement sits | the pleading-special-matters rule | not applicable |
| Notice of filing | must be promptly served, with proof filed | not applicable |
| Manner of serving the notice | MCR 2.107 if appeared; MCR 2.105 if not | not applicable |
| Deadline to challenge a notice of intent | with the first response, by answer or motion | not applicable |
| Deadline to challenge an affidavit | 63 days from service | not applicable |
| Challenge to the signer's qualifications | expressly within the 63 days | Rule 702, near trial |
| Form of challenge | motion under MCR 2.119 | not applicable |
| Late challenge | only for good cause allowed by the court | not applicable |
| Amendment of the affidavit | under MCR 2.118 and MCL 600.2301 | not applicable |
There is nothing like this in the federal rules. A federal medical malpractice case tests the expert at summary judgment or under Rule 702; Michigan tests the paperwork in the first two months and then closes the window.
A short checklist
- File the affidavit and then serve notice of the filing. They are separate obligations.
- Check whether the other side has appeared before choosing MCR 2.107 or MCR 2.105 service.
- File proof of service promptly. The rule requires it in terms.
- If you are the defendant, decide the notice-of-intent challenge before your first response — that is the deadline, whether you answer or move.
- Diary 63 days from service of any affidavit you receive, and put the expert's qualifications on the list of things to check inside that window.
- Challenge by motion under MCR 2.119. Raising it in passing does not count.
- Do not rely on good cause. It is available, but it is the court's to allow, not yours to assume.
- If your own affidavit is attacked, look at MCR 2.118 — amendment is expressly contemplated.
Where these rules live
- MCR 2.105 — Process; Manner of Service
- MCR 2.107 — Service and Filing of Pleadings and Other Documents
- MCR 2.112 — Pleading Special Matters
- MCR 2.118 — Amended and Supplemental Pleadings
- MCR 2.119 — Motion Practice
This page explains what the court rule says; it is not legal advice. The affidavit's required contents and the expert-qualification standards are set by statute — MCL 600.2912d, 600.2912e and 600.2169 — which this site does not carry, and they should be read alongside the rule.