(a) Amendments Before Trial.
(1) Amending as a Matter of Right. A party may amend its pleading once as a matter of right
(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 no hearing has been set, the party may amend it at any time within 20 days after it was served.
(2) Amending by Leave of Court. A party who cannot amend under Rule 28(a)(1) may amend by written agreement of all parties or may request the court’s permission to amend. Leave to amend will be freely given when justice requires.
(3) Proposed Pleading as an Exhibit. A party moving for leave to amend a pleading must attach a copy of the proposed amended pleading as an exhibit to the motion. The exhibit must show how the proposed pleading differs from the existing pleading by bracketing or striking through the text to be deleted and underlining the text to be added.
(4) Filing and Response. If a motion for leave to amend is granted, the moving party must file and serve the amended pleading within 10 days after the entry of the order granting the motion, unless the court orders otherwise. An opposing party must respond to an amended pleading, if a response is required, within the time remaining for response to the original pleading or within 10 days after the amended pleading is served, whichever is later, unless the court orders otherwise.
(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 may grant a continuance to enable the objecting party to respond to the evidence.
(2) For Issues Tried by Consent. When an issue not raised by the pleadings is introduced at trial by the parties’ express or implied consent, it must be treated in all respects as if it had been raised in the pleadings. A party may request, at any time, to amend the pleadings to conform to the evidence. Failure to amend does not affect the result of the trial of that issue.
(c) Relation Back of Amendments. An amendment relates back to the date of the original pleading if the amendment asserts a claim or defense that arose out of the conduct, transaction, or occurrence set forth, or attempted to be set forth, in the original pleading.
(d) Supplemental Pleadings. On motion and reasonable notice, the court may permit a party to file a supplemental pleading setting forth any transaction, occurrence, or event that happened after the date of the pleading to be supplemented. A court may permit supplementation even though the original pleading is defective in stating a claim for relief or defense. The court may order the opposing party to answer or otherwise respond to the supplemental pleading within a specified time.