(1) A party may amend a pleading once as a matter of course within 14 days after being served with a responsive pleading by an adverse party, or within 14 days after serving the pleading if it does not require a responsive pleading.
(2) Except as provided in subrule (A)(1), a party may amend a pleading only by leave of the court or by written consent of the adverse party. Leave shall be freely given when justice so requires.
(3) On a finding that inexcusable delay in requesting an amendment has caused or will cause the adverse party additional expense that would have been unnecessary had the request for amendment been filed earlier, the court may condition the order allowing amendment on the offending party's reimbursing the adverse party for the additional expense, including reasonable attorney fees.
(4) Amendments must be filed in writing, dated, and numbered consecutively, and must comply with MCR. Unless otherwise indicated, an amended pleading supersedes the former pleading.
(B) Response to Amendments. Within the time prescribed by MCR, a party served with an amendment to a pleading requiring a response under MCR must
(1) serve and file a pleading in response to the amended pleading, or
(2) serve and file a notice that the party's pleading filed in response to the opposing party's earlier pleading will stand as the response to the amended pleading.
(C) Amendments to Conform to the Evidence.
(1) When issues not raised by the pleadings are tried by express or implied consent of the parties, they are treated as if they had been raised by the pleadings. In that case, amendment of the pleadings to conform to the evidence and to raise those issues may be made on motion of a party at any time, even after judgment.
(2) If evidence is objected to at trial on the ground that it is not within the issues raised by the pleadings, amendment to conform to that proof shall not be allowed unless the party seeking to amend satisfies the court that the amendment and the admission of the evidence would not prejudice the objecting party in maintaining his or her action or defense on the merits. The court may grant an adjournment to enable the objecting party to meet the evidence.
(D) Relation Back of Amendments. An amendment that adds a claim or a defense relates back to the date of the original pleading if the claim or defense asserted in the amended pleading arose out of the conduct, transaction, or occurrence set forth, or attempted to be set forth, in the original pleading. In a medical malpractice action, an amendment of an affidavit of merit or affidavit of meritorious defense relates back to the date of the original filing of the affidavit.
(E) Supplemental Pleadings. On motion of a party the court may, on reasonable notice and on just terms, permit the party to serve a supplemental pleading to state transactions or events that have happened since the date of the pleading sought to be supplemented, whether or not the original pleading is defective in its statement of a claim for relief or a defense. The court may order the adverse party to plead, specifying the time allowed for pleading.
Mich. Ct. R. 2.118