Since the late 1990s, the Innocence Project (founded by Barry Scheck & Peter Neufeld) has been responsible for over 100 exonerations using DNA evidence. Many of the convictions had occurred before DNA techniques became available. However, alarmingly, the Innocence Project has reported that over half of its first 70 exonerations also had involved police misconduct & nearly 50 percent of them had involved prosecutorial misconduct.
However, most occurrences of wrongful conviction do not involve DNA evidence. According to a recent study by the Center for Public Integrity, since 1970, individual judges & appellate court panels cited prosecutorial misconduct as a factor when dismissing charges, reversing convictions or reducing sentences in over 2,000 cases. In another 500 cases, appellate judges offered opinions ? either dissents or concurrences ? in which they found misconduct warranted a reversal. In thousands more cases, judges labeled prosecutorial behavior inappropriate, but upheld convictions using a doctrine called "harmless error". The nature of the questionable conduct includes: courtroom misconduct; mishandling of physical evidence (hiding, destroying or tampering with evidence, case files or court records); failing to disclose exculpatory evidence; threatening, badgering or tampering with witnesses; & using false or misleading evidence.
In January 1999, the Chicago Tribune published a five-part series of articles that found, in the paper’s own words, "nearly 400 cases where prosecutors obtained homicide convictions by committing the most unforgivable kinds of deception. They hid evidence that could have set defendants free. They allowed witnesses to lie. All in defiance of the law. Prosecutors swear to seek the truth but instead many pursue convictions at any cost. The premium is on winning, not justice." The series, reported & written by Maurice Possley & Ken Armstrong, documented 381 cases, going back to 1963, in which courts reversed murder convictions because prosecutors presented evidence they apparently knew to be false, or concealed evidence suggesting innocence, or both.
Then, in November 1999, the Tribune published another in-depth series by Armstrong & reporter Steve Mills that examined murder cases in which Illinois prosecutors, mostly in Cook County (Chicago), had charged a defendant with a capital crime & asked for the death penalty. The journalists identified 326 reversals attributed in whole or part to the misconduct of the prosecutors. As in the first series, the reporters named names ” of prosecutors, forensic scientists, & others within the criminal justice system. They wrote about how prosecutors used confessions extracted through police torture, used perjured testimony of jailhouse informants seeking rewards, or used unreliable analyses from law enforcement forensic laboratories. In addition to changing perceptions, these reporters & their editors changed public policy. Most notably, in 2003, Illinois Governor George Ryan took the unprecedented action of commuting the sentences of everyone on death row to life imprisonment.