Trial and Error: Learning from Patterns of Mistakes
The Supreme Court has emphasized that "the trial is the paramount event for determining the guilt or innocence of the defendant." (Herrera v. Collins, 506 U.S. 390, 416 (1993).) On the other hand, the court has noted that in our adversarial system, "the Constitution entitles a criminal defendant to a fair trial, not a perfect one." (Delaware v. Van Arsdall, 475 U.S. 673, 681 (1986).) While no trial may be completely "perfect," some trial errors are more harmful than others. With the benefit of modern DNA tests, we know that even at a seemingly "fair trial," an innocent person can be convicted. Every few weeks another innocent person is walked out of prison, freed by DNA testing on old evidence. Looking back at the criminal trials of those innocent people, one might expect to find out that weak evidence was used to convict them, since, after all, they were not actually guilty. Perhaps jurors were swayed by sinister details of the rapes and murders with which the defendants were charged. However, when reading the transcripts of those trials, one finds that jurors were not always so wrong to convict based on the seemingly solid evidence that they heard. Only years later did DNA tests show that this trial evidence was in fact deeply flawed. In retrospect, we can unravel how what the jurors saw was misleading. Grave errors were cemented before trial, during the criminal investigation, and crucial evidence was contaminated or even concealed, making cases seem far stronger than they should have been to the jurors. Even seemingly powerful testimony by a trial witness--- an informant recalling the defendant's confession, a detective describing a confession in custody, and an eyewitness pointing out the defendant from the stand-can be tainted by unreliable procedures commonly used by police across the country. A few representative examples from wrongful conviction cases illustrate flaws in our criminal procedure and how states can effectively reform criminal procedure to make our criminal trials less error-prone.