The study, which was published Monday, analyzed the results of new DNA testing from 634 sexual assault and homicide cases that took place in Virginia between 1973 and 1987. DNA testing was not available at the time the crimes occurred, but the study was possible because a state forensic serologist - who processed biological evidence in serious criminal cases - had retained some physical evidence, such as cotton swabs and clothing swatches.
When these old pieces of evidence were subjected to DNA testing, 5 percent of those convicted were exonerated of the crime. When only sexual assault cases were considered, the number of those exonerated jumped even higher. DNA testing supported the exoneration of between 8 and 15 percent of those convicted of a sexual crime.
Previous research had put the rate of wrongful conviction around three percent. But a difference in methodology may explain the disparity between the two estimates.
Lemon told the Associated Press that the results from the Virginia study could most likely be applied to the rest of the nation. Source
The report acknowledged certain limitations. For instance, it said that in two-thirds of the cases the samples didn't have enough DNA for testing. Roman said that may mean the number of false convictions is much higher.
Roman said there likely are "dozens, if not hundreds, of people who were convicted erroneously; dozens, if not hundreds, of people who were not convicted of a crime they committed who may have gone on to commit new crimes; and there were dozens, if not hundreds, of people who thought they had justice as a victim of a horrible crime who didn't." Source
I group this under the umbrella term of false allegations although wrongly convicted might be more fitting here.
And one huge document that I picked from my to do pile. As usual, the more interesting data points:
False Rape Allegations: An Assault On Justice by Bruce Gross, PhD, JD, MBA - The Forensic Examiner - 2009
Although there is no doubt that false rape allegations occur, it is extremely difficult to determine what percentage of rape reports is intentionally false. This is due to many factors, including jurisdictional variation in definition, criteria, and reporting practices, as well as the fact that not all rapes are reported. Although the FBI had set 8% as the average rate of false (actually, unfounded) accusations during the late 1990s, there is remarkable variation in the estimates of false allegations of rape found in the literature (Kanin, 1994; Epstein, 2005). A review of those studies on false rape accusations conducted between 1968 and 2005 showed a percentage range from 1-90% (Rumney, 2006).
Very little formal research has been conducted on the prevalence of false allegations of rape. One study looked at the 109 cases of forcible rape that were disposed of in one small midwestern town between 1978 and 1987 (Kanin, 1994). The given town was specifically selected for study because the police department used a uniquely objective and thorough protocol when investigating rape complaints. Among other procedural safeguards, officers did not have the discretion to drop rape investigations if they concluded the complaint was "suspect" or unfounded. Every rape accusation had to be thoroughly investigated and included offering a polygraph to both the accuser and the accused. Cases were only determined to be false if and when the accuser admitted that no rape occurred.
The researchers further investigated those cases that the police, through their investigation, had ultimately determined were "false" or fabricated. During the follow-up investigation, the complainants held fast to their assertion that their rape allegation had been true, despite being told they would face penalties for filing a false report. As a result, 41% of all of the forcible rape complaints were found to be false. To further this study, a similar analysis was conducted on all of the forcible rape complaints filed at two large midwestern public universities over a 3-year period. Here, where polygraphs were not offered as part of the investigatory procedure, it was found that 50% of the complaints were false.
Charles P. McDowell, a researcher in the United States Air Force Special Studies Division, studied the 1,218 reports of rape that were made between 1980 and 1984 on Air Force bases throughout the world (McDowell, 1985). Of those, 460 were found to be "proven" allegations either because the "overwhelming preponderance of the evidence" strongly supported the allegation or because there was a conviction in the case. Another 212 of the total reports were found to be "disproved" as the alleged victim convincingly admitted the complaint was a "hoax" at some point during the initial investigation. The researchers then investigated the 546 remaining or "unresolved" rape allegations including having the accusers submit to a polygraph. Twenty-seven percent (27%) of these complainants admitted they had fabricated their accusation just before taking the polygraph or right after they failed the test. (It should be noted that whenever there was any doubt, the unresolved case was re-classified as a "proven" rape.) Combining this 27% with the initial 212 "disproved" cases, it was determined that approximately 45% of the total rape allegations were false.
Unfortunately, like the two studies presented here, the empirical studies that exist on the frequency of false rape allegations are sparse in number and have notable limitations. Small sample sizes and non-representative samples preclude generalizability. Regardless, the mere number of publicized incidents of false accusations of rape over the last two decades indicates not only a need for further investigation into the problem, but a better understanding of how to identify such cases. [...]
The most frequent context and motive for the fabricated rape was consensual sex with an acquaintance that led to some sort of problem for the accuser. The perceived problem was typically something that caused feelings of shame and guilt in the accuser (such as contracting a sexually transmitted disease or becoming pregnant), which was bound to be discovered and received negatively by family or friends.
Approximately half of the accusers who were motivated by a need for an alibi identified the alleged rapist. Their goal was not to harm or cause problems for the acquaintance, but to protect themselves in what they perceived to be a desperate situation. As with most lies, the false rape accusation allowed the accuser to deny responsibility by creating an alternate reality into which to escape.
The next most common reason for lying about being a victim of rape was revenge, rage, or retribution. In the Midwest study, this included 27% of the non-student and 44% of the student accusers. In these cases, the false victim had suffered some real or perceived wrong, rejection, or betrayal by the alleged rapist. As the purpose of making the accusation was to obtain some measure of revenge, the "suspect" was always identified. Researchers in the Air Force study also found that spite or revenge and the need to compensate for a sense of personal failure through an alibi accusation were the primary motives for false rape reports.