This study defined wrongful conviction as only those cases in which a person was convicted of a felony, but later exonerated, generally due to evidence previously not available or confession from the culprit. The data consisted of 205 legal cases from 1900 on gathered from books, documents, and newspaper clippings. Nearly 45 percent of these wrongful convictions were for murder, 30.5 percent for robbery, and 12.1 percent for forcible rape. The most frequent kind of error was eyewitness misidentification, accounting for more than 52 percent of all cases. Other major factors were perjury by witnesses, negligence by criminal justice officials, pure error, and coerced confessions. A single reason pervading many wrongful convictions was police and prosecutorial overzealousness. The authors argue that the higher the level in the system the case reaches, the less chance that an error will be discovered and corrected unless it involves issues of constitutional rights and due process. Tables and 16 references. (Author abstract modified)