5th Cir. R. 28.4 — Supplemental Briefs: the court's own rule, verbatim from RULES and INTERNAL OPERATING PROCEDURES OF THE UNITED STATES COURT OF APPEALS FOR THE FIFTH CIRCUIT (December 2025), official PDF, sha-custodied. Court-level requirement: applies to appeals in the U.S. Court of Appeals for the Fifth Circuit alongside the Federal Rules of Appellate Procedure.
The rules do not permit the filing of supplemental briefs without leave of court, but there are some occasions, particularly after a case is orally argued or submitted on the summary calendar, where the court will call for supplemental briefs on particular issues. Also, where intervening decisions or new developments should be brought to the court's attention, counsel may direct a letter, not a supplemental brief, to the clerk with citations and succinct comment. See FED. R. APP. P. 28(j). If a new case is not reported, copies of the decision should be appended. The letter must be filed in 4 copies, and served on opposing counsel.
The rules do not permit the filing of supplemental briefs without leave of court, but there are some occasions, particularly after a case is orally argued or submitted on the summary calendar, where the court will call for supplemental briefs on particular issues. Also, where int