A reply brief in appellate practice is the appellant’s optional final written submission in the standard briefing cycle, filed after the appellee’s response to rebut what that response said. Under Federal Rule of Appellate Procedure 28(c), you are not required to file one, but silence on a point the appellee raised can read as concession, and unanswered arguments have time to settle with the panel before oral argument.1Legal Information Institute. Federal Rules of Appellate Procedure Rule 28 – Briefs The job is narrow: respond to the appellee, do not rehash the opening, and do not raise anything new.
What a Reply Brief Can and Cannot Do
The reply exists to answer the specific arguments in the appellee’s brief. It sharpens the dispute by showing the panel exactly where the two sides disagree on the law or the facts.
What it cannot do is introduce legal theories or factual arguments that were not part of the opening brief or the appellee’s response. Courts refuse to consider new issues raised for the first time at this stage because the appellee has no chance to answer within the normal schedule. A reply that wanders into new territory will be ignored or struck in that portion. After the reply, no further briefs may be filed unless the court grants leave on motion, and that permission is rare.1Legal Information Institute. Federal Rules of Appellate Procedure Rule 28 – Briefs
Should You File One
In most appeals, yes. If the appellee’s brief makes factual claims you can disprove, cites cases you can distinguish, or mischaracterizes the record, leaving those assertions unchallenged is a gamble. A focused reply also previews the issues you plan to emphasize at argument, and judges and clerks often review it immediately before the hearing.
The rare exception is an appellee brief so weak that an earnest rebuttal would lend it credibility it has not earned. That situation is uncommon; most response briefs raise at least one argument worth answering.
Deadlines
Federal Rule of Appellate Procedure 31(a)(1) gives the appellant 21 days after the appellee’s brief is served to file a reply. There is also a hard backstop: the reply must be filed at least seven days before oral argument, even if the 21-day window has not closed.2Legal Information Institute. Federal Rules of Appellate Procedure Rule 31 – Serving and Filing Briefs
State appellate courts set their own timelines, and the range varies. Some allow as few as 10 days, others 20 or more. Check the specific court’s local rules.
Extensions
If you need more time, Rule 26(b) allows the court to extend the deadline for good cause on motion, with proof of service on all parties. Courts respond better to motions filed before the deadline expires than to motions explaining why you missed it. Common grounds include the complexity of the issues raised in the response, intervening legal developments, or circumstances outside counsel’s control.3Legal Information Institute. Federal Rules of Appellate Procedure Rule 26 – Computing and Extending Time
Word Limits and Formatting
A federal reply brief may not exceed 6,500 words, exactly half the 13,000-word principal brief limit. In monospaced typeface, the limit is 650 lines. A brief of 15 pages or shorter is not subject to the type-volume limit. Any brief above 15 pages must include a certificate of compliance stating the word or line count, and you can rely on your word processor’s count.4Legal Information Institute. Federal Rules of Appellate Procedure Rule 32 – Form of Briefs, Appendices, and Other Papers
Rule 32 also sets physical requirements:
- 8½ by 11 inch paper with at least one-inch margins on all sides.
- Proportionally spaced fonts must be serif and at least 14-point. Monospaced fonts may not exceed 10½ characters per inch. Sans-serif type is permitted only in headings and captions.
- Double-spaced text, though block quotations longer than two lines, headings, and footnotes may be single-spaced.
- Gray cover for reply briefs, which lets the court identify the document’s role in the briefing sequence at a glance.
- Plain roman type, with italics or boldface reserved for emphasis. Case names must be italicized or underlined.
State courts often diverge on cover color, word limits, and font rules, so check local requirements separately.4Legal Information Institute. Federal Rules of Appellate Procedure Rule 32 – Form of Briefs, Appendices, and Other Papers
What Goes Inside
Rule 28(c) requires every reply brief to include a table of contents with page references and a table of authorities listing every case, statute, and other authority cited, with the pages where each appears. Cases must be arranged alphabetically. These tables eat into your word count, so factor them in early.1Legal Information Institute. Federal Rules of Appellate Procedure Rule 28 – Briefs
The substantive argument section is where the real work happens. Identify the strongest claims in the appellee’s brief: factual mischaracterizations, cases cited out of context, and legal standards applied incorrectly. Every factual assertion in your reply should be supported by a record citation, including transcripts, exhibits, and lower court filings. If the appellee quoted testimony selectively or ignored evidence that cuts against them, set the record straight with precise page references.
When the appellee relies on case law, explain why those cases are distinguishable: different facts, different procedural posture, or a legal principle that does not extend as far as claimed. Equally valuable is highlighting concessions, including implicit ones. If the response quietly dropped an argument the lower court relied on, say so. Judges notice when a party abandons a position.
Where to Spend the 6,500 Words
The word limit forces hard choices. Trying to answer every point in the appellee’s brief produces a scattered document and wastes the opportunity. Focus on arguments that could actually change the outcome, and let minor quibbles go. A better approach is to identify the two or three arguments the appellee made that, if accepted, would sink your appeal, and dismantle those thoroughly.
Contesting the Standard of Review
If the appellee argues that a deferential standard applies, such as abuse of discretion rather than de novo review, the reply is your last chance to push back on that framing. The standard controls how much deference the appellate court gives the lower court’s decision, and it often decides the appeal before the merits analysis begins. An appellant who loses the standard-of-review fight faces an uphill climb on everything else.
Countering Harmless Error
Appellees frequently argue that even if the lower court erred, the mistake did not affect the outcome. This defense can neutralize a clearly proven error, so the reply needs to meet it directly. The counter depends on the type of error. Structural errors, which affect the entire framework of the proceeding, require automatic reversal without harmless error analysis; examples include denial of the right to counsel or the right to a public trial.
For non-structural errors, the appellant must show the mistake actually mattered. On direct review of constitutional errors, the government bears the burden of proving the error was harmless beyond a reasonable doubt. Emphasize any reasonable possibility that the error influenced the outcome, and frame the impact in concrete terms: specific testimony, a jury instruction, the weight of the remaining evidence. That lands harder than abstract arguments about fairness.
Cross-Appeals Use a Different Sequence
If both sides have appealed, the standard three-brief cycle does not apply. Federal Rule of Appellate Procedure 28.1 sets a four-brief sequence:
- The appellant files a principal brief in the appeal.
- The appellee files a combined brief serving as the principal brief in the cross-appeal and the response to the appellant’s brief.
- The appellant files a combined brief responding to the cross-appeal and, optionally, replying to the response in the main appeal.
- The appellee may file a reply brief limited to the cross-appeal.
That final reply must be filed within 21 days after the appellant’s response and reply brief is served, but no later than seven days before argument. No further briefs are permitted without leave of court.5Legal Information Institute. Federal Rules of Appellate Procedure Rule 28.1 – Cross-Appeals The combined briefs are longer and more complex than a standard reply, and the interleaving of offensive and defensive arguments demands careful organization.
Filing and Post-Filing
Federal appellate courts and many state systems use the Case Management/Electronic Case Files (CM/ECF) system. Filing is not complete until the system generates a notice of electronic filing; that notice is your proof of submission and your timestamp.6United States Courts. Electronic Filing (CM/ECF) A certificate of service must accompany the brief. Some courts still require a specified number of paper copies in addition to the electronic filing, so check local rules.
Supplemental Authority After Filing
If a relevant decision comes down or a statute changes after you have filed, Rule 28(j) lets you file a letter alerting the court. The letter identifies the new authority, explains its relevance, and points to the page of your brief or the point in oral argument it supports. The body cannot exceed 350 words, footnotes included, and the opposing party may file an equally limited response.1Legal Information Institute. Federal Rules of Appellate Procedure Rule 28 – Briefs
A 28(j) letter is not a second reply brief. Courts reject letters that use new authority as a vehicle for additional argument. Identify the authority, give the citation, and state in a sentence or two why it matters. The 350-word ceiling enforces that discipline. Once the reply is in and no supplemental filings are pending, the court either schedules oral argument or decides the case on the briefs.