Eighteen percent of the more than 2,000 persons known to have been exonerated of crimes — not just found to have been convicted in flawed legal proceedings: exonerated — had pleaded guilty. As of 2020, according to the Innocence Project, of 375 convicts exonerated by DNA evidence, 11.7 percent had pleaded guilty. Many of the exonerees, caught up in an intimidating process that can be fast-moving and bewildering, were from racial minorities.
A consequence of excessive plea bargaining is, the ABA’s report says, that “police and government misconduct often goes unchecked because so few defendants proceed to pre-trial hearings where such misconduct is litigated.” Furthermore, prosecutors become less skeptical of their witnesses, and less scrupulous about not advancing weak cases. Defense lawyers become less rigorous in investigating cases that seem destined for a plea deal. With such deals, defendants waive the right to confront adverse witnesses, and perhaps to challenge unconstitutionally procured evidence and to receive materials prosecutors acquired during discovery.