Part XVII: Rules Governing Actions Filed in the Complex Commercial Litigation Division · Last amended March 20, 2026 · Last verified July 28, 2026
(a) Amendments Before Trial.
(1) Amendments as a Matter of Course. A party may amend the party’s pleading once as a matter of course without leave of Court:
(A) at any time before a responsive pleading is served; or
(B) if the pleading is one to which no responsive pleading is required and the action has not been set for trial, no later than 20 days after the pleading is served.
(2) Other Amendments. In all other cases, a party may amend its pleading only with the opposing party’s written consent or the Court’s leave. The Court should freely give leave when justice so requires.
(3) Form of Amendments. A party must file an amended pleading with the Court, even if the Court has granted a motion for leave to file the amended pleading. A party filing an amended pleading must also file a document indicating plainly how the amendment differs from the pleading that it amends.
(4) Effect of an Amended Pleading on Other Parties’ Claims. An amended pleading has no effect on another party’s counterclaims, crossclaims, or third-party claims, which are preserved and do not need to be re-filed.
(5) Time to Amend After Certain Motions and Consequence of Not Amending.
(A) If a party wishes to amend the party’s complaint in response to a motion to dismiss under Rule 12(b)(6), the party must amend the party’s complaint – or seek leave to amend – either:
(i) Before the party’s response to the motion is due; or
(ii) If the case has been transferred from another court, within 30 days after the transfer, even if the party responded to the motion in the other court.
If a party neither amends nor moves to amend by the time set forth in Rule 143(a)(5)(A), a dismissal under Rule 12 (b)(6) shall be with prejudice – but only as to the named party – unless the Court for good cause shown dismisses the complaint without prejudice.
(6) Time to Respond to Amended Pleading. Unless the Court orders otherwise, any required response to an amended pleading must be made within the time remaining to respond to the original pleading or within 10 days after service of the amended pleading, whichever is later.
(b) Amendments During and After Trial.
(1) Based on an Objection at Trial. If, at trial, a party objects that evidence is not within the issues raised in the pleadings, the Court may permit the pleadings to be amended. The Court should freely permit an amendment when doing so will aid in presenting the merits and the objecting party fails to satisfy the Court that the evidence would prejudice that party’s action or defense on the merits. The Court may grant a continuance to enable the objecting party to meet the evidence.
(2) For Issues Tried by Consent. When an issue not raised by the pleadings is tried with the parties’ express or implied consent it must be treated in all respects as if raised in the pleadings. A party may move – at any time, even after judgment – to amend the pleadings to conform to the evidence and to raise an unpled issue. But failure to amend does not affect the result of the trial of that issue.
(c) Relation Back of amendments. An amendment to a pleading relates back to the date of the original pleading when:
(1) The law that provides the applicable statute of limitations allows relation back;
(2) The amendment asserts a claim or defense that arose out of the conduct, transaction, or occurrence set out – or attempted to be set out – in the original pleading; or
(3) The amendment changes the party or the naming of the party against whom a claim is asserted, if Rule 143(c)(2) is satisfied and within 120 days of the filing of the complaint, or such additional time the Court allows for good cause shown, the party to be brought in by amendment:
(A) has received such notice of the institution of the action that the party will not be prejudiced in maintaining a defense on the merits; and
(B) knew or should have known that, but for a mistake concerning the identity of the proper party, the action would have been brought against the party.
(d) Supplemental Pleadings. On a motion the Court may permit a party to serve a supplemental pleading setting out any transaction, occurrence or event that happened after the date of the pleading to be supplemented. The Court may permit supplementation even though the original pleading is defective in stating a claim or defense. If the Court permits the supplemental pleadings, the opposing party must respond within 10 days after service of the pleading.
Adopted, Mar. 13, 2026, effective Mar. 20, 2026.
Rule 143(a) starts with the easy case: a party may amend a pleading once as a matter of course, without leave of Court, either before a responsive pleading is served or, if no response is required and the case isn't set for trial, within 20 days after the pleading is served. Every other amendment needs the opposing party's written consent or the Court's leave, which the Court should give freely when justice calls for it. An amended pleading has to be filed even after the Court grants leave, paired with a document showing plainly how it differs from what it amends, and it leaves untouched any other party's counterclaims, crossclaims, or third-party claims.
Rule 143(a)(5) adds real teeth around motions to dismiss: if a party wants to amend a complaint in response to a Rule 12(b)(6) motion, the party has to amend, or seek leave to amend, before the response to that motion is due (or within 30 days of a transfer from another court). Miss that window without amending or moving to amend, and a Rule 12(b)(6) dismissal comes down with prejudice as to that party, unless the Court dismisses without prejudice for good cause. A response to an amended pleading is due within whatever time remained on the original pleading or 10 days after service of the amendment, whichever comes later.
Rule 143(b) covers amendments that surface once trial has started: an objection that evidence falls outside the pleadings can lead the Court to allow an amendment, with a continuance available if the objecting party needs one to meet the new evidence, and an issue tried by the parties' consent is treated as if it had been pleaded from the start even if no one ever moves to amend. Rule 143(c) sets the relation-back rules that let a later amendment reach back to the original filing date: when the limitations law itself allows it, when the new claim or defense grew out of the same conduct or occurrence already pleaded, or when a new party is being named, provided that party got notice within 120 days of the complaint (or longer for good cause) and knew or should have known the suit belonged against it but for a mistake in identity. Rule 143(d) closes with supplemental pleadings, letting a party add later-arising events by motion, even over a defective original pleading, with a 10-day response deadline once the Court allows it.