Exculpatory evidence is evidence favorable to the defendant in a criminal trial that exonerates or tends to exonerate the defendant of guilt. It is the opposite of inculpatory evidence, which tends to present guilt.

In many countries, including the United States, police and prosecutors are required to disclose to the defendant exculpatory evidence they possess before the defendant enters a plea (guilty or not guilty). In some countries such as Germany, the prosecutor has to actively search for both exculpatory and inculpatory circumstances and evidence before filing of action.

Per the Brady v. Maryland decision, prosecutors in the United States have a duty to disclose exculpatory evidence even if not requested to do so. While the prosecution is not required to search for exculpatory evidence and must disclose only the evidence in its possession, custody, or control, the prosecution's duty is to disclose all information known to any member of its team, e.g., police, investigators, crime labs, et cetera. In Brady v. Maryland, the U.S. Supreme Court held that such a requirement follows from constitutional due process and is consistent with the prosecutor's duty to seek justice. The Brady doctrine is a pretrial discovery rule that was established by the United States Supreme Court in Brady v. Maryland (1963). The rule requires that the prosecution must turn over all exculpatory evidence to the defendant in a criminal case. Exculpatory evidence is evidence that might exonerate the defendant.