Legal and social science research and technology are improving their methods for identifying and understanding the wrongful conviction of defendants. Opinion and studies reach various conclusions about the prevalence of these miscarriages of justice. Whether more should be done to prevent them is also a matter of opinion. Nevertheless, few dispute the fundamental value of accumulating knowledge on how errors were made and how they can be avoided and remedied.
After making a case for the existence and consequences, nearly all research on wrongful convictions searches for causes, the factors across cases that drive these errors. Some studies rely on social science methods. Other authors use experience-based argument. The research highlights below attempt to summarize some of these findings without commenting on their approach or their conclusions. Studies were organized under two broad headings:
These are contributing factors within the justice system itself. They include police practices, management of evidence, styles of interacting with witnesses, the credibility of forensic evidence, judicial predispositions, adverse influences on juries, and the competence and conduct of prosecutor and defense attorneys.
These contributing factors involve social and psychological forces that can distort normal, sound professional and bureaucratic practices. A particularly heinous sexual homicide, for example, may increase the pressures for swift action by law enforcement, investigative, prosecutorial, jury, and judicial representatives that later prove to have been biased against the defendant.
More than a decade ago, Huff et al. (1996) reviewed data from 500 cases of wrongful conviction and attempted to estimate the percentage of all convictions that may be in error. Rattner (1988) conducted an early study of the types of crimes associated with wrongful convictions. Although numerous cases of wrongful convictions have been documented in the literature and in the media, criminologists have yet to devise a methodology for estimating the extent of such errors in the criminal justice system. Poveda (2001) reviewed the methodology of studies on this question, and concluded it to be a “dark figure.” Ramsey et al. (2007) sampled criminal justice professionals on the subject of wrong conviction prevalence. Estimates fell in the range of one-half to one-percent. Respondents believed a rate below one-half of one percent was acceptable.
There has been a recent surge of interest in the retrospective study of wrongful conviction. Campbell et al. (2004) conducted in-depth interviews of five defendants, who identified problematic professional and bureaucratic practices. Their accounts of survival during incarceration and adaptation after release offer insights into the consequences of wrongful conviction. Grounds (2006) studied the psychological effects of wrongful conviction and imprisonment in a descriptive study of 18 men referred for psychiatric assessment after their convictions were quashed. Substantial psychological disability was found. Weisman (2006) provides and insightful study of how denying an offense and rejecting statements of remorse work against wrongfully convicted defendants.
Huff (2004) expressed the belief in the importance of developing a better understanding of wrongful conviction and its causes not only to protect the rights of the innocent, but also to protect citizens from being victimized by offenders who remain free while the wrongly convicted are sent to prison.
It has been argued that wrongful convictions and the publicity surrounding their release could actually lower the deterrence of laws and prosecution, particularly in areas where crime is endemic. Fon, et al., 2007 argued that these convictions erode respect for the judicial system. Lando (2005) disputes the implication that convictions in error have any effect on potential offenders. Garoupa et al. (2012) believe that convictions in error do harm the deterrence of laws and punishment, but that by compensating the wrongfully convicted, this effect may be mitigated. Issues surrounding civil claims for wrongful conviction were reviewed by Garrett et al, 2009). Norris (2011) has also reviewed how compensation statutes relate to exonerees. Ravenell (2009 found that persons wrongly convicted of crimes who bring actions for an erroneous arrest, detention, or conviction are often denied monetary compensation.
Zalman et al. (2012) sought to examine how citizens view this problem. Using data from a statewide survey of Michigan residents, the study reported on citizens’ attitudes regarding the issue of wrongul conviction. Overall, the results suggested that respondents not only recognized the incidence of wrongful conviction but also believed that such errors occur with some regularity. Further results showed that respondents believed wrongful convictions occur frequently enough to justify major criminal justice system reform.
Kennedy, et al. (2004) reasoned that legal systems have to live with the possibility of error. With technology advances, all parties in the systems must proceed as though their conclusions may be reversed in the future. The failure of government to act and the need to counteract complacency are themes of Naughton’s (2001) own analysis of the subject.
Anderson (1998) believes that wrongful conviction can be traced back to professional and bureaucratic wrongdoing within the justice system, which includes the targeting practices of the police, the suppression of evidence, coercion and intimidation of witnesses, falsified forensic evidence, judicial malpractice, jury tampering, and prosecution and defense misconduct. Bell (2008) concluded that eyewitness misidentification and police and lawyer behaviors (e.g., tunnel vision) are contributors to this problem. Medwed (2006) echoes beliefs that many of the same conditions exist, especially as they relate to eyewitness misidentification, the use of jailhouse informants, ineffective assistance of counsel, and racial bias.
Prosecutorial misconduct is one of the leading causes, or contributing causes, of wrongful convictions, contended Joy (2006). Joy argued that prosecutorial misconduct is not chiefly the result of isolated instances of unprincipled choices or the failure of character on the part of some prosecutors. Rather, prosecutorial misconduct is largely the result of three institutional conditions: vague ethics rules that provide ambiguous guidance to prosecutors, vast discretionary authority with little or no transparency, and inadequate remedies for prosecutor misconduct.
False confessions are a great concern among those who have reviewed cases of wrongful conviction. Leo et al. (2010) reviewed research on the issue and discussed how law enforcement and investigator practices can generate false confessions. Authors described how “coercion error,” “contamination error,” “misleading special knowledge,” “tunnel vision,” and “confirmation bias” lead police and others to ignore the possibility that a confession is false. McCann (1998) also looked at confession evidence. A framework is offered to categorize confessions according to a number of dimensions, including whether or not a confession is retracted, veracity or truthfulness, legal culpability of the suspect, voluntariness, and specific nature of the coercion that might produce a confession. A proposal is made for a new subtype of false confession, the coerced–reactive type, to supplement curent theoretical approaches.
Collins et al. (2008) examined the accuracy of claims that faulty forensic science is a leading cause of wrongful convictions by reviewing conviction reversals achieved in the Innocence Project. Only 11% of the cases involved forensic malpractice. In 18% of these cases, forensic evidence actually favored the convicted defendant. Garrett (2009) saw more evidence of error in a study of exonerees. Apparently, 60% of prosecution experts in this study provided invalid testimony at trial. This testimony involved 72 forensic experts and 52 labs in 25 states.
So-called “junk science” and scientific fraud have been contributors to erroneous convictions, according to Giannelli (2011), who reviewed convictions reversed with new DNA analyses. Even scientifically sound procedures can be misrepresented when they are misused or incompetently reported.
Enforcement action is needed to reduce and prevent adverse practices (Anderson, 1998). Authors conclude that government responses to these practices have been insufficient (Denov et al., 2005)
Bell (2008) investigated the impact of criminal justice education on law student knowledge about wrongful conviction. Survey findings showed education raised awareness of the fallibility of evidence, but not necessarily of the types of professional practices that can lead to conviction errors.
Greater scientific oversight of forensic analysis is needed, according to research by Garrett, et al. (2009). Giannelli (2011) argues for written protocols and other policies and procedures that will be followed by all analysts. These conclusions are shared by Saks et al. (2005).
Several authors conclude that systemic social inequality causes certain individuals and groups to become socially, politically, and economically discriminated against and to feel and act powerless in the judicial system (Anderson, 1998, Bell, 2008)
Pre-trial publicity has always been a concern of courts. Greene et al. (1998) demonstrated in controlled studies that jurors may evaluate the probability of a defendant’s guilt by the ease with which similar or relevant examples come to mind from recent media.
Leo et al. (2009) conducted a review of literature on the causes of wrongful convictions and found the contributing issues fell into three categories, the manner in which false confessions were generated by police interrogation, individual differences in susceptibility to interrogative influence, and the role false confessions have played in documented wrongful convictions of the innocent. They examined seven psychological processes linking false confessions to wrongful conviction and failures of post-conviction relief:
The authors discuss how these factors bias the perceptions and behaviors of others in the system not directly involved in the context where contributing issues emerged. Martin (2004) provides additional analysis of the effects of “tunnel vision”, or “investigator bias,” and “jailhouse informers” on erroneous convictions.
Though not reviewed in this compilation, false memory research is a related field to that of wrongful convictions. Loftus (2003) raised concern about criminal convictions that are based largely on the testimony of victims or witnesses in the absence of confirmatory evidence.
Defendants who are marginalized in the judicial system because of their education, race, economic status, mental condition, or abilities should have equal access to expert testimony, regardless of their ability to pay, some authors argue (Anderson, 1998).