Founder
Updated: September 2026
As a general rule, you cannot introduce new evidence on appeal in a criminal case. An appellate court reviews what happened in the trial court using the existing record rather than hearing new witnesses or considering evidence discovered afterward. However, newly discovered evidence can still affect a conviction through other procedures, and an appellate ruling may result in the case returning to the trial court.
Can You Introduce New Evidence on Appeal?
In general, no. A direct appeal is not a second trial and does not provide another opportunity to present evidence.
Instead, the appellate court reviews the existing trial court record to determine whether legal errors occurred and whether those errors justify relief. That record may include trial transcripts, admitted exhibits, motions, and court orders.
Because appellate review is generally limited to that record, evidence that was never presented to the trial court typically cannot be introduced for the first time on appeal.
What Happens If New Evidence Is Found During a Trial?
When new evidence is discovered while a criminal trial is still underway, the trial court may have an opportunity to address it before the case reaches an appeal. What happens depends on the evidence, when it was discovered, and why it was not disclosed or located earlier.
For example, the defense may seek to introduce newly located evidence while the trial is ongoing. If prosecutors failed to disclose favorable evidence that they were legally required to provide, the defense may also ask the trial court for an appropriate remedy.
Addressing the issue at the trial level is important because it can affect both the proceedings themselves and the record available for a later appeal.
How Can Newly Discovered Evidence Affect a Criminal Case After Trial?
Although new evidence generally cannot be introduced directly on appeal, evidence discovered after a conviction may still provide a basis for seeking relief.
Illinois law provides other ways to raise certain claims after a conviction. Under the state’s Post-Conviction Hearing Act, a defendant may bring qualifying constitutional claims before the trial court. Newly discovered evidence may also form the basis of an actual innocence claim.
Most post-conviction petitions are subject to filing deadlines, with limited exceptions. Actual innocence claims are treated differently. They are exempt from the Act’s general filing limitation and may instead be brought within a reasonable period after conviction.
To support an actual innocence claim, the evidence generally must be:
- Newly discovered and unavailable earlier through due diligence
- Material and not merely cumulative
- Sufficiently conclusive that it would probably change the result on retrial
How newly discovered evidence should be raised depends on the nature of the evidence, when it came to light, and the procedural history of the case.
What If Evidence Was Improperly Excluded at Trial?
Evidence that the trial judge excluded is different from evidence discovered for the first time after trial. If your attorney attempted to introduce evidence and the judge improperly excluded it, that ruling may itself become an issue on appeal.
The appellate court can review whether the trial judge applied the law correctly. Depending on the error and its effect on the case, the reviewing court may reverse the judgment or send the case back to the trial court for further proceedings.
Similarly, if the prosecution improperly withheld evidence favorable to the defense, the nondisclosure may raise a constitutional claim. Depending on when the withheld evidence is discovered and the procedural posture of the case, there may be a legal avenue for seeking relief.
Can New Evidence Be Introduced in a Retrial?
Yes. If a conviction is reversed and the case is remanded for a new trial, the parties may have an opportunity to present evidence that was not heard during the original trial, subject to the rules of evidence and other applicable law.
A retrial is different from an appeal because the case is once again before a trial court that can receive testimony and exhibits. Depending on why the conviction was reversed, newly discovered evidence could therefore become part of the case.
A new trial is not always the ultimate outcome. The prosecution may decide not to retry the case, or the court’s ruling may require different proceedings.
When New Evidence Surfaces After a Conviction
Finding new evidence after a conviction raises an important question: what is the proper way to get that evidence before a court? The answer depends on when it was discovered, what it shows, and the procedural history of your case.
The attorneys at The Keleher Appellate Law Group handle criminal appeals and post-conviction matters in Illinois. If new evidence has surfaced or you believe evidence was improperly excluded or withheld, contact our legal team to discuss what options may be available.