Introducing new evidence on appeal is possible only in narrow circumstances. Appellate courts decide cases on the record built at trial, so as a rule they will not look at anything that was not already before the trial judge. A handful of exceptions exist for evidence that could not have been found earlier, evidence the prosecution suppressed, proof that trial counsel was constitutionally deficient, fraud on the court, and facts a court can judicially notice. Each requires a formal motion, a demanding showing, and compliance with a strict deadline.
Why the Default Answer Is No
An appeal is a review of what already happened, not a new hearing. The higher court works entirely from the “record on appeal,” which under federal rules consists of the original papers and exhibits filed in the trial court, any transcript of proceedings, and a certified copy of the docket entries.1Legal Information Institute. Federal Rules of Appellate Procedure Rule 10 – The Record on Appeal Appellate judges do not hear live testimony, examine physical evidence, or watch witnesses on cross-examination. Their job is to decide whether the trial court made legal errors on the record it had.
Exceptions That Can Open the Door
Courts recognize that a rigid rule can produce unjust outcomes, so several exceptions exist. None is easy to meet.
Newly Discovered Evidence
This is the most commonly invoked exception. It applies when evidence surfaces after trial that the party could not have found earlier despite reasonable efforts. The word that matters is “could not.” Evidence that was available but overlooked will not qualify.
Prosecutorial Suppression (Brady Material)
In criminal cases, the prosecution must disclose evidence favorable to the defendant that is material to guilt or punishment, regardless of good or bad faith.2Justia US Supreme Court. Brady v. Maryland, 373 U.S. 83 (1963) A defendant who learns after trial that favorable evidence was withheld can use that discovery to seek a new trial, provided the suppressed evidence was significant enough to undermine confidence in the verdict.
Ineffective Assistance of Counsel
A defendant may introduce evidence showing that trial counsel’s performance was constitutionally deficient. The standard requires two showings: that counsel’s performance fell below an objective standard of reasonableness, and that there is a reasonable probability the outcome would have been different with competent representation.3Justia US Supreme Court. Strickland v. Washington, 466 U.S. 668 (1984) Because the evidence of counsel’s failures rarely appears in the trial record itself, courts sometimes allow it to be developed outside the ordinary appellate process.
Fraud on the Court
If a party or witness intentionally deceived the trial court and the deception affected the outcome, the opposing party may present evidence of that fraud. Courts apply this exception sparingly, and the party alleging fraud carries a heavy burden.
Judicial Notice
An appellate court can take judicial notice of certain facts at any stage of a proceeding, effectively adding information to the record without a formal evidentiary submission. This works only for facts not reasonably subject to dispute, either because they are commonly known or because they can be verified from unquestionable sources. A court might notice that a particular date fell on a Tuesday or that an agency published a specific regulation. It will not notice contested facts central to the case. Either party can request judicial notice, and the opposing party is entitled to be heard before the court acts.4Legal Information Institute. Federal Rules of Evidence Rule 201 – Judicial Notice of Adjudicative Facts
The Four-Part Test for Newly Discovered Evidence
Federal courts apply a well-established test, and all four requirements must be met.
First, the evidence could not have been obtained before trial ended even with reasonable effort. This due diligence requirement is where most motions fail. If the evidence sat in a public database, was held by someone the party could have contacted, or would have turned up through standard investigation, the court will reject it. The question is not whether the party actually knew about it, but whether a reasonably diligent person in their position would have found it.
Second, the evidence cannot be cumulative. A witness saying what several others already said does not justify reopening the case.
Third, the evidence cannot be offered solely to attack a witness’s credibility. Impeachment material alone will not support a new trial on this theory.
Fourth, the evidence must be significant enough that it would likely have produced a different verdict or a lighter sentence. Interesting but unlikely to change the outcome is not enough.
Deadlines That Can Close the Door Anyway
Even qualifying evidence will be rejected if the motion is late. The deadlines vary sharply by case type.
Criminal Cases
In federal criminal cases, a motion for a new trial based on newly discovered evidence must be filed within three years after the guilty verdict. If an appeal is pending, the trial court cannot grant the motion until the appellate court sends the case back.5LII / Legal Information Institute. Federal Rules of Criminal Procedure Rule 33 – New Trial States set their own limits for cases in state court.
Civil Cases
Civil deadlines are much tighter. A standard motion for a new trial must be filed within 28 days after entry of judgment.6Legal Information Institute. Federal Rules of Civil Procedure Rule 59 – New Trial; Altering or Amending a Judgment Evidence discovered after that window closes falls under a separate relief-from-judgment provision, which must be used no later than one year after entry of judgment. The party must also show they could not have discovered the evidence in time to file the earlier motion despite reasonable diligence.7Legal Information Institute (LII). Federal Rules of Civil Procedure Rule 60 – Relief from a Judgment or Order
Habeas Corpus Petitions
Federal prisoners face a one-year filing deadline for habeas petitions. When the claim rests on newly discovered facts, that year runs from the date the facts could have been discovered through reasonable diligence, not from the date of conviction.8Office of the Law Revision Counsel. 28 USC 2255 – Federal Custody; Remedies on Motion Attacking Sentence
Habeas Corpus as a Separate Path
A direct appeal and a habeas corpus petition are different proceedings, and treating them as one is a common mistake. A direct appeal asks a higher court to review the trial record for legal errors. A habeas petition is a separate civil action challenging whether the petitioner’s imprisonment is lawful, and it sometimes allows evidence a direct appeal would not.
When a defendant has exhausted direct appeals and later uncovers evidence pointing to actual innocence, habeas may be the only remaining route. To pass through the actual innocence gateway, the petitioner must show that in light of the new evidence, it is more likely than not that no reasonable juror would have found them guilty beyond a reasonable doubt.9Justia US Supreme Court. Schlup v. Delo, 513 U.S. 298 (1995) A second or successive petition adds another layer: the petitioner must first get authorization from a panel of appellate judges and make a preliminary showing that the evidence, if proven, would establish by clear and convincing evidence that no reasonable factfinder would have found them guilty. The appellate court acts on that request within 30 days, and its decision is not further appealable.10Office of the Law Revision Counsel. 28 USC 2244 – Finality of Determination
How to Actually Ask the Court
Presenting new evidence on appeal requires a written motion that spells out precisely why the court should depart from the normal rule. Federal appellate rules require any motion to state the grounds for relief with particularity, include the legal argument, and attach any affidavit or supporting document needed to back it up. An affidavit filed with the motion must contain factual statements only and may not include legal argument.11Legal Information Institute. Federal Rules of Appellate Procedure Rule 27 – Motions
The opposing party has 10 days after service to respond, and the moving party has 7 days to reply.11Legal Information Institute. Federal Rules of Appellate Procedure Rule 27 – Motions The court can deny the motion, which is the most common outcome. It can grant the motion and consider the evidence itself. Or it can remand to the trial court to hold a hearing and determine the evidence’s impact. Remand is often the most practical path because the trial court is equipped to hear testimony and resolve factual disputes.
Plain Error Is a Different Remedy
Not every problem with a trial requires new evidence. Appellate courts can notice and correct obvious errors that no one raised below. Under the federal rules, a plain error affecting substantial rights may be considered even though it was never brought to the trial court’s attention.12Legal Information Institute. Federal Rules of Criminal Procedure Rule 52 – Harmless and Plain Error This doctrine does not introduce new evidence, but it can produce a similar corrective result when the existing record already reveals a serious mistake. It applies most often in criminal cases involving incorrect jury instructions or evidence admitted under the wrong legal standard.