After-discovered evidence, or newly discovered evidence, is evidence which existed at the time of the original trial but was only discovered after the conclusion of the trial. After-discovered evidence is an issue predominantly in criminal proceedings and may be used as the basis for a motion for a new trial.
Courts employ a four-part test in determining whether to grant a new trial on this basis. Namely, courts consider whether the new evidence: (1) could not have been have obtained prior to the conclusion of the trial by the exercise of reasonable diligence; (2) is not merely corroborative or cumulative; (3) will not be used solely to impeach the credibility of a witness; and (4) would likely result in a different verdict or lighter sentence if a new trial were granted. Under the third element, courts determine whether new evidence is corroborative based on the strength of the other evidence supporting the conviction; new evidence is less likely to be deemed cumulative if the conviction was largely based on circumstantial evidence. Lastly, the evidence must also be admissible.
For example, the Supreme Court of Florida has held that newly discovered DNA evidence and confessions of another suspect were sufficient to compel a new trial, because the evidence weakened the case against the defendant enough to give rise to a reasonable doubt as to their culpability.
Under Rule 59 of the Federal Rules of Civil Procedure, after-discovered evidence may be used to challenge judgments in civil proceedings as well, such as foreclosure actions. In such instances, courts employ a similar standard that considers whether the evidence could have been discovered during the proceeding and would have produced a different result. However, changes in law or interpretations of the law are generally not accepted as after-discovered evidence.
Lastly, under the model rules of professional responsibility, prosecutors who learn of "new, credible and material evidence creating a reasonable likelihood that a convicted defendant did not commit an offense of which the defendant was convicted" must disclose the evidence or remedy the conviction.
See also: Writ of coram nobis
[Last updated in December of 2021 by the Wex Definitions Team]