Rate of wrongful convictions in the United States

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"wrongful conviction rates" redirects here. For other uses, see wrongful conviction rates (disambiguation).

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The actual rate of wrongful convictions in the United States is not known, but potentially high enough to warrant significant policy changes. Among the millions in the United States with a felony conviction record, scholars cited here estimate between 0.0016% and 15.4% are wrongly convicted. The estimated rate climbs much higher when including conviction reversals for those on death row avoiding wrongful execution.

The range suggests as few as 35 prisoners are factually innocent to as many as 300,000 or more current prisoners are wrongly convicted. When including those with felony convictions who completed their sentence or were never incarcerated, the highest estimate nears to three million in the United States whose rights remain curtailed by a wrongful conviction.

Differences in these estimates reflect the scholar's definition of a wrongful conviction, types of cases focused upon, their methodology, institutional context, biases and other subtle differences. Once their estimate suggests the extent of the problem, their discussions spill over into better understanding the causes of wrongful convictions. And then disputes over what policy changes, if any or to what degree, should arguably follow.

Range of estimated rates

While recognizing conviction error is not only a U.S. problem, the specific wrongful conviction rate anywhere remains unknown and unknowable. No legal or other scholar anywhere claims the criminal justice process of any jurisdiction never convicts an innocent person. They dispute how many become wrongly convicted. Scholars of diverse academic fields offer a variety of approaches to how best calculate an estimated range of wrongful convictions.

Calculating the estimate

To understand how these scholars arrive to such different conclusions, it helps to recognize each contributors' institutional contexts, their possible activism, the types of cases they focus upon, their definition of wrongful conviction, and any apparent ideological or other bias. The scholar's ideology and institutional context tends to affect how they define a wrongful conviction.

Source

Calculated estimates derive from reputable sources. The title of each source is provided with a link. Most are freely accessible online.

• Academic article: A scholarly study published in an academic journal, such as a law review or criminology journal.
• Research report: A federally funded research report, typically by the U.S. Department of Justice, Office of Justice Programs.
• Other: Something other than the above items, such as an estimated rate coming from a U.S. Supreme Court opinion.

Methodology

This emerging scholarship attempts to calculate an estimated rate of wrongful convictions in the United States using available information and various research methods, typically the following five types.

• Matched samples: Contrasting a sample of known exonerations or known conditions for wrongful convictions (numerator), with data involving a matching population of all convictions during the same period (denominator). Typically involving cases with DNA profiling.
• Self-reporting: Asking criminal justice officials or prisoners to fill out a survey, and then controlling for self-reporting bias.
• Qualitative: Examining the context in which errors occur, both false positives and false negatives, typically addressing limits in the quantitative approaches mentioned above.
• Public records: Examining available court records, such as documentation of conviction reversals for capital cases.
• Other: Something other than a rigorous methodology, such as quoting another source.

Year

Year of publication demonstrates scholarly interest since the rapid rise in the U.S. incarceration rate occurring simultaneously with the 1990s drop in crime and the advent of DNA-based exonerations. The year of publication typically reflects the number of known exonerations at the time, and its implications for the emerging scope of conviction errors. Academic arguments for a low prevalence of wrongful conviction were easier to defend early in the innocence movement, when innocence critics could anticipate DNA testing had discovered just about every factually innocent case. As the rate of exonerations soared, relying less on clear-cut DNA evidence, these innocence critics noted an "expansion of exoneration" to include those still morally culpable yet legally not guilty. More recent scholarship typically addresses this definitional issue.

Authorship

Authorship comes from those either within the criminal justice system—such as judges or prosecutors—and those from without, such as law professors, criminologists, federally funded researchers, and innocence activists.

Institutional context

The authors' role, at least at time of their contribution, suggest if incentivized to see a low or high rate of significant criminal justice errors. Those working within the criminal justice system present a different perspective than those working outside of it. Especially when defining an actionable wrongful conviction.

• Judicial: Scholars working within the criminal justice system typically narrow wrongful conviction to "actual innocence" (or factual innocence) to calculate their estimate. Wrongful convictions (type I "false positive" errors) typically occur in the context of trying to avoid wrongful acquittals (type II "false negative" errors). If responsible for the public's safety while routinely encountering certain types of violence, you are understandably incentivized—even if unconsciously—to err on the side of caution. Blackstone's ratio may seem an impractical ideal.
• Nonjudicial: Scholars outside of the criminal justice system, largely innocence activist law professors and criminologists without any custody responsibilities, may include "legal exoneration" that generally casts a wider net for their calculated findings. Innocence activists concerned by the "dark figure of crime" of unreported offenses are just as concerned over the growing "dark figure of innocence" of unknown wrongful convictions in that same place and time. Concern extends to victims of crimes and potential victims, recognizing how wrongful convictions allow actual perpetrators to commit more crime.

Basic range of criminal justice outcomes, along a normative distribution curve

Defining "wrongful conviction"

• Actual innocence: Or factual innocence, where the convicted person played no role in the charged offense.
• Legal exoneration: Reversal of the conviction due to procedural error suggesting prosecutorial or judicial overreach, while leaving questions about the convicted person's culpability.

Addressing bias

Since good scholarship seeks to be aware and transparent of its own limits, some of each source's limitations are briefly addressed.

Calculations

How the source derived the estimated rate from its methodology is briefly summarized. See the sourced article for how the authors specifically calculated their estimate.

Table of scholarly estimates

No.	Rate	Source	Method	Year	Author(s)	Institutional context	Defining "wrongful conviction"	Addressing bias	Calculations
1	0.0016–1.95%	Academic article: The Myth of Factual Innocence	Qualitative	2007	Morris B. Hoffman	Judicial: Served as District Judge, Second Judicial District (Denver), State of Colorado	Actual innocence; the minority of defendants at trial typically contest moral guilt (their level of culpability) rather than actual guilt	Excluding the bulk of plea deals skews Hoffman's figure downward. In a footnote, he admits this could be problematic. While admitting his figure has flaws, he presses the point that a popular notion declaring half of all convictions as innocent is far more deeply flawed.	Hoffman starts with a lower range by carving out the 95% rate of plea deals. While admitting plea deals involve false confessions, he discounts their impact to 1 in 100. Just because one falsely confesses to a more serious charge for a plea deal doesn't mean they're not guilty of some culpability. That leaves 5% of jury trial outcomes to calculate significant wrongful convictions. If juries were only 80% right, Hoffman grants as a stretch, that leaves only 1% for an overall wrongful conviction rate. Add in that "1 out of 100 innocent-but-pleading" percentage (95% x 1/100, plus 1%), he offers 1.95% as the upper limit of wrongful convictions. For the lower end, Hoffman cites the 500 exoneration known at the time of the article. If a quarter of the two million trials resulted in acquittals over a 20-year period since the innocence movement began, that yields a .0033% rate (500/1,500,000). With only 5% of cases tried, that figure drops to .0016%.
2	0.016–0.062%	Academic article: Overstating America's Wrongful Conviction Rate? Reassessing the Conventional Wisdom About the Prevalence of Wrongful Convictions	Qualitative	2018	Paul G. Cassell	Judicial: Formerly served as the U.S. District Judge in Utah. At time of authorship, Cassell served as the Distinguished Professor of Law at the S.J. Quinney College of Law at the University of Utah. He is a recognized victim's rights proponent.	Actual innocence: excluding mere legal innocence. Cassell takes issue with moral culpability present in some publicized wrongful conviction cases.	Cassell raises a concern shared by others: how overestimated error rates could hinder prosecuting the truly guilty.	Cassell calculates a much lower rate using what he calls the "component-parts methodology", by looking at three components: error rates at trial, given at .005; the ratio of wrongful convictions obtained through trials versus plea bargains, given as 20/80; and the percentage of cases resolved through pleas, given as 5/95. Hence, .005 x 20/80 (or .25) x 5/95 (or .052632) = .000066, or "0.0066%, or 0.66 wrongful convictions out of 10,000 guilty pleas". As Cassell explains, "Then, using a weighted average to calculate the overall wrongful conviction rate—i.e., the 0.0066% wrongful conviction rate in guilty-plea cases and the 0.50% wrongful conviction rate in trials—leads to a wrongful conviction rate of .00031, or 0.031%, or 3.1 out of 10,000 violent crime convictions. Of course, this wrongful conviction rate is not precise. To avoid any suggestion of false precision, the wrongful conviction rate might be stated as a range, running from 50% below to 100% above the .031% rate—i.e., a wrongful conviction range of 0.016% to 0.062%."
3	0.027%	U.S. Supreme Court opinion: Kansas v. Marsh	Other (quoting an opinion piece)	2006	U.S. Supreme Court Justice Antonin Scalia, quoting from Joshua Marquis	Judicial: At time of authorship, Scalia served as a U.S. Supreme Court Justice. Marquis served as an Oregon district attorney.	Actual innocence. As Marquis puts it, "they didn't do it, weren't there, didn't participate."	Scalia cites 0.027% from quoting a New York Times opinion piece penned by Joshua Marquis. In this article quoted by Scalia in Kansas, Marquis challenges a 2005 article by Gross et al. that raised the alarm of a potentially high rate of wrongful convictions. In his concurring opinion, Scalia decries how his dissenting Kansas colleagues rely heavily on that Gross article, with "its inflation of the word 'exoneration'." Most of the scholars in this academic debate criticize the shortcomings in this figure. For example, Roman et al. point out how the numerator and denominator Marquis uses in his opinion piece retorting Gross et al. do not correspond to the same sampled population.	In his 2006 editorial, Marquis glibly counters Gross et al. (2005) by granting there could be up to ten times as many who are actually innocent among the 15 million felony cases prosecuted from 1989 to 2003. He throws out 4000 for that 10x figure, implied as a stable rate (i.e., 667 in each of those 15 years). 4000 divided by 15,000,000 = .027% (or a 99.973% success rate). This .027% figure is not from carefully analyzed empirical data, but rather from Marquis's hypothetical retort to Gross et al. (2005). Marquis presents the figure to belittle that article's findings for potentially higher rates resulting in wrongful convictions in the "thousands, perhaps tens of thousands". Marquis criticizes Gross et al. for defining exoneration "as an official act declaring a defendant not guilty of a crime for which he or she had previously been convicted". That same year, Scalia in Kansas cites Marquis's critique of this expansive definition along with Marquis's number as an available figure supporting his view that arguably "the system works". Gross et al. (2005), penned mostly by law professors, followed 340 DNA-based and non-DNA exonerations as examples of an increasing rate of wrongful convictions from 1989 to 2003. In response that year, Marquis decried "the myth of innocence" exemplified in legal exonerations that often include other elements of criminality or moral culpability. This "exoneration inflation" fuels much of the early divide between scholars working within the criminal justice system and those outside of it. Scalia's suspiciously low rate has spurred further scholarly debate on how to best estimate the probable rate of wrongful convictions in the U.S. criminal justice system. Apparently in response to this critique, subsequent scholarly estimates typically narrow to factual innocence, with cautiously conservative estimates. Some of that discussion is captured in these cited academic articles and in the further reading material below.
4	0.5–1%	Academic article: Qualitatively Estimating the Incidence of Wrongful ConvictionsZalman, M. (2012), Qualitatively estimating the incidence of wrongful convictions. Criminal Law Bulletin, 48:2, 219-279. (PDF)</ref>	Qualitative	2012	Marvin Zalman	Nonjudicial: Zalman serves as a criminal justice professor at Wayne State University.	Actual innocence, or "factual innocence" and not "procedurally defective convictions".	Zalman attempts to strike a balance between justice system actors and innocence critics on the one hand, who insist convictions of factual innocence are too "exceedingly rare" to warrant sweeping reforms, and "ideologically driven innocence activists" on the other hand, who propose responsive policy prescriptions.	Zalman introduces a qualitative approach. He notes the limits faced by other scholars seeking a scientifically-based rate, based on limited data from more serious offenses. Bypassing a quantitative approach, he cites previous estimates from justice system professionals where 71.8% surveyed estimated an error rate under 1% and 20.3% estimated error 1-5% of convictions. But then takes other complementary inputs into account, nodding to more recent scholarship. Zalman offers a "generalized and nation-wide assumption" between one-half of one percent (.0005 or 0.5%) and one percent (.01 or 1%) for all felony convictions are factually innocent. He describes this as a subjective estimate "not directly derived from the opinions of the justice system professionals surveyed". A 0.5% rate was originally published in 1996 by Ronald Huff, a colleague of Rattner, based on his survey of justice system personnel. His finding raised an early alarm that up to 10,000 innocent defendants were being convicted each year. Of the 1,993,880 convictions in 1990, 0.5% results in an estimated 9,969 false convictions. Huff considered this a conservative estimate, since most respondents were prosecutors and law enforcement officials with an apparent self-interest to defend conviction accuracies. Ramsey & Frank followed up this effort (see below).
5	0.5 – 3%%	Academic article: Perceptions of Criminal Justice Professionals Regarding the Frequency of Wrongful Conviction and the Extent of System ErrorsRamsey, R.J.; Frank, J. (2007), Perceptions of criminal justice professionals regarding the frequency of wrongful conviction and the extent of system errors. Crime & Delinq, 53:3, 437-470.</ref>	Self-reporting	2007	Robert H. Ramsey and James Frank	Nonjudicial: Serve as criminologist professors, Ramsey at Indiana University East and Frank at University of Cincinnati.	Actual innocence: "For purposes of the survey, the term wrongful conviction is defined as people who have been convicted of a criminal offense but are in fact innocent" and this definition was included in the survey sent to respondents.	This study seeks to improve on previous self-reporting studies (Rattner, 1983, and Huff et al., 1986) by including the perspective of defense attorneys.	A 53-item survey was sent to 1,500 criminal justice professionals in Ohio. Police, prosecutors, judges, and defense attorneys were asked to rate specific types of error or misconduct that could lead to wrongful convictions. For each type of error, respondents rated how often, from 1 (never) to 9 (always), they believed those in the named group committed that type of error. Ramsey & Frank tabulates these responses by type of perceived error and type of criminal justice official. When aggregated into mean scores, survey results indicated a perception of 1% to 3% wrongful convictions occurring throughout the United States. But only .5% to 1% occurring in their own jurisdictions. While the overall range spans from .5% to 3%, most respondents (78% overall) admit anything over .5% is unacceptable. Less than 2% of respondents countenanced error rates of 4% or more.
6	2.3%	Academic article: Frequency and Predictors of False Conviction: Why We Know So Little, and New Data on Capital Cases	Matched samples	2008	Samuel R. Gross and Barbara O'Brien	Nonjudicial: Gross served (and continues to serve) as law professor at the University of Michigan Law School, and editor of the National Registry of Exonerations project, where he continues to serve. O'Brien served as Assistant Professor of Law (and now as a full professor) at the Michigan State University College of Law and now also serves as an editor to the National Registry of Exonerations.	Legal exoneration, exoneration as officially pardoned, dismissed or acquitted; recognizing this could possibly include exonerees who participated to some degree in the crime, the authors are confident these are too few to discount exoneration as a useful proxy for innocence. They offset such cases by those who agreed during post-conviction relief to accept lesser non-capital sentences despite likely full innocence. They assert "there are many more false convictions than exonerations."	Gross and O'Brien offer no perspective for criminal justice personnel, observing capital cases from an external perspective. They mention variability of geography (jurisdiction differences), mental illness, and race, but do not focus on these.	Gross & O'Brien use death row exonerations data that occurred after Furman invalidated death penalty statutes. Capital cases provide ample data to compare exonerated with non-exonerated cases. Among the 2,394 sentenced to death from 1973 to 1984, and processed for post-conviction relief by 2004, 54 were exonerated (54/2394) = 2.3%. Among the 3,792 capital cases processed 15 years prior to 1989, 86 were exonerated (86/3792) = 2.3%. Death row cases receive extraordinary level of attention. Gross & O'Brien concede this increases the likelihood of exoneration. Once an innocent defendant is removed from death row to a life sentence or other outcome, they note, exoneration becomes less likely. Applying this 2.3% estimate to non-capital cases appears less certain.
7	3.3 – 5%	Academic article: Innocents Convicted: An Empirical Justified Factual Wrongful Conviction Rate	Matched samples	2007	D. Michael Risinger	Nonjudicial: Risinger served (and continues to serve) as Professor of Law at Seton Hall University School of Law. He has served professionally in various roles in the legal field, developing an expertise on evidence. He regards himself as an Innocence Network activist.	Legal exonerations, implied as factually innocence; since exonerations result from DNA evidence, specifically in rape-murder capital cases.	Risinger admits his motive is to challenge Scalia's and Marquis's low estimate of 0.027% (see above).	Risinger looks at capital rape-murders committed in the 1980s to establish an empirically-based wrongful conviction rate. Available data from this period can be compared to establish a numerator of exonerations to a denominator of all relevant cases. For his numerator, Risinger looks at DNA exonerations in cases from 1982 to 1989 for reliable data. He finds 14 exonerated cases, but reduces this down to 11 qualifying DNA-based rape-murder cases. He further reduces this by half a case to control for error, resulting in a 10.5 numerator. For his denominator, Risinger starts with 479 capital rape-murder cases in this period. He reduces this total by a third, the approximate percentage of rape-murder cases without usable DNA, resulting in 319. 10.5/319 = .0032881, or 3.3% for his minimum estimate. For his maximum estimate of 5%, Risinger cuts short a near doubling of the 3.3 floor to a 6.4% (moving toward a qualitative approach). To mitigate potential overestimation, he believes actual innocence runs reasonably as high as 5%. He considers his 3.3 to 5% a "conservative minimum factual innocence rate".
8	4.1%	Academic article: Rate of False Conviction of Criminal Defendants Who are Sentenced to Death	Matched samples	2014	Samuel R. Gross, Barbara O'Brien, Chen Hu, and Edward H. Kennedy	Nonjudicial: Gross served as law professor at the University of Michigan Law School, and editor of the National Registry of Exonerations project, where he continues to serve. O'Brien served as Assistant Professor of Law at the Michigan State University College of Law and now also serves as an editor to the National Registry of Exonerations. Chen Hu served as senior biostatistician at the American College of Radiology Clinical Research Center. Kennedy served as statistician from the University of Pennsylvania School of Medicine Department of Biostatistics and Epidemiology.	Legal exoneration: "Exoneration under threat of execution is defined as exoneration that resulted from legal proceedings that were initiated before the end of 2004 and while the defendant was under sentence of death."	Gross et al. insist this calculated error rate is a conservative estimate, hinging on undercounts of innocent defendants. As they admit, "The main source of potential bias is the accuracy of our classification of cases as true or false conviction."	Gross et al. follow the same 1973-2004 capital cases data utilized in their 2008 study, as also used by Risinger (above). They focus on death-sentenced defendants who remained under threat of execution from 1973 through 2004. "[F]alse convictions are far more likely to be detected among those cases that end in death sentences than in any other category of criminal convictions," they explain. Gross et al. use the Kaplan–Meier estimator to calculate the percentage of wrongly convicted who remain on death row for the 21 years between 1973 and 2004. They hypothesized that the longer these defendants remained on death row, the greater the chance they would ultimately be exonerated. They took into account those cases removed from death row for various reasons. They found the likelihood of exoneration for this population of capital cases that remained under threat of execution throughout this 21-year period to be 4.1%, or somewhere between 2.8 and 5.4% within a 95% confidence interval.
9	5–15%	Research report (of federally funded study): Post-Conviction DNA Testing and Wrongful Conviction	Matched samples	2012	John Roman, Kelly Walsh, Pamela Lachman, and Jennifer Yahner.	Nonjudicial: Contributors are listed as working for the Urban Institute. Roman and Walsh are each identified as having a PhD.	Actual innocence, where exoneration is not due merely to procedural errors, but where "the person convicted is factually innocent of the charges".	The study admits to data limitations. The data being used lacked contextual information for the collected physical evidence, undermining the evidentiary value of the DNA testing results. Their follow-up report (below) addresses this shortcoming.	Retrospective DNA testing of physical evidence was funded by the U.S. Dept of Justice on sexual assault and homicide cases in Virginia from 1973 to 1987. Of the original 534,000 cases reviewed, only around 3,000 elicited physical evidence. These were narrowed to 2,100 where a suspect was identified. Cases with a usable DNA profile dropped the number of eligible cases below 800. Eligible cases were subjected to DNA testing for one of four outcomes: 1) indeterminate, 2) inculpatory, 3) exculpatory but insufficient, and 4) exculpatory supporting exoneration. Of the 715 cases with a usable DNA profile, testing eliminated 56 of the convicted offender as the source. 56/715=7.8%. Where testing appears to support exoneration, 38 eliminated the convicted offender as the source. 38/715=5.3%. Where applied to homicides and sexual assault cases with exculpatory DNA testing supporting exoneration = 5% of convictions. Where applied to an unbiased sample of sexual assault convictions with exculpatory DNA testing supporting exoneration = 8 to 15% of convictions.
10	6%	Academic article: Measuring Self-Reported Wrongful Convictions Among Prisoners	Self-reporting	2018	Charles E. Loeffler, Jordan Hyatt and Greg Ridgeway	Nonjudicial: Loeffler and Ridgeway served as Associate Professors of Criminology, and Hyatt served as a research associate, all three at the University of Pennsylvania. Hyatt has since moved to Drexel University to serve as an Assistant Professor of Criminology.	Actual innocence: Factual innocence, meaning respondent indicated they had zero involvement in their most recent conviction.	To date, this finding only represents one sampling of the Pennsylvania prison population. A replication study, especially for other populations, may produce different results. Self-reporting bias from respondents appear far less apparent than the popular notion that all prisoners claim they are innocent.	Loeffler et al. dared to ask the prisoners themselves about their level of criminality. They surveyed nearly 3,000 prisoners entering the Pennsylvania state prison system. With assurances of anonymity, knowing their answers could never be traced back to them individually, respondents were surprisingly frank about their criminal history. Two-thirds of respondents expressed full responsibility for their instant offense. One-fourth admitted partial responsibility. Only eight percent declared zero involvement in their most recent conviction. Accuracy of these responses were compared with data from prison staff, which remained highly aligned. Implausible responses were mitigated with statistical adjustments, dropping the 8% to 6%. Additionally, the study illuminates the variability among conviction types. From only a 2% conviction error rate among DUI cases to 40% in rape convictions. The findings mirror the RAND Note published in 1978 that found only 15% of prisoners claimed actual innocence. (See Poveda's 15.4% rate below.)
11	11.6%	Research report (of federally funded study): Estimating the Prevalence of Wrongful Conviction	Matched samples	2017	Kelly Walsh, Jeanette Hussemann, Abigail Flynn, Jennifer Yahner, and Laura Golian.	Nonjudicial: The publication only states these are authors to this summary technical report. Walsh and Yahner also listed authors in the prior Urban Institute 2012 report (see above).	Actual innocence: "In this study, since DNA evidence is the tool used to detect wrongful convictions, we are solely concerned with those where factual innocence is the issue," according to the original 2012 study (see below).	This study seeks to counter sampling bias inherent in other approaches to find a false conviction rate (see above). It bypasses individual claims by examining available DNA evidence upfront. Its relatively higher rate likely reflects its narrow focus on sexual assault cases.	Walsh et al. utilize a U.S. Justice Department grant to revisit a 2012 Urban Institute report (above), "Post-Conviction DNA Testing and Wrongful Conviction". This study determined the estimate could be safely generalized to other states besides Virginia. Its original 430 cases with a sexual assault component yielded 231 DNA findings for post-conviction review. Of these, 29 cases (12.6%) produced exculpatory DNA evidence sufficient enough to support exoneration. Probability weights corrected this rate of sexual assault cases to 11.6%.
12	15.4%	Academic article: Estimating Wrongful Convictions	Self-reporting	2001	Tony G. Poveda	Nonjudicial: Sociology Professor in the Criminal Justice department at SUNY Plattsburgh	Actual innocence: "Did no crime" response, suggesting a self-reported response of factual innocence, while those admitting some culpability were excluded from findings.	Self-reported innocence raises red flags, yet the willingness to report more criminality than reported in official records suggests the data is not as biased as one may presume. The high rates reported for rape and sexual-assault-other-than-rape (see table below) align closely with a previous study finding 41% of forcible rapes reported to police in one U.S. city during a nine-year period did not factually occur.	Poveda utilized the RAND Inmate Survey which sampled inmates from prisons in California, Michigan and Texas. 2,190 prisoners filled out a questionnaire that was then compared to official prison records, showing remarkable agreement. Prisoner respondents reported more criminality than revealed in their official records. One of the questions asked respondents about their current conviction. The next question invited respondents to indicate their level of culpability. The last option for respondents to check was "Did no crime". Poveda analyzed these answers to calculate the rates of self-reported denial of convicted offenses. The date showed wide variance depending on the type of offense, as illustrated in the following table. With minimal variance by state (14.1% in MI, 14.6% in CA, 16.7% in TX), respondents reported an overall "did no crime" rate of 15.4%. SEE TABLE BELOW, displaying rates by each case type.
13	68%	Academic article: Capital Attrition: Error Rates in Capital Cases,1973-1995	Public records (statistical study of appeals in capital cases)	2000	James S. Liebman, Jeffery Fagan, Valerie West, and Jonathan Lloyd	Nonjudicial: Lieban served as Professor of Law at Columbia Law School, Fagan served as Professor of Public Health at Columbia University and visiting Professor at Columbia Law School, West was a doctoral candidate at New York University, and Lloyd was a JD candidate at Columbia Law School.	Legal exoneration: Reversal of capital case convictions, to avoid wrongful executions, often reduced to a non-capital sentence.	This study focuses more on wrongful executions in the U.S. than wrongful exonerations. "This much error, and the time needed to cure it, impose terrible costs on taxpayers, victims' families, the judicial system, and the wrongly condemned. And it renders unattainable the finality, retribution and deterrence that are the reasons usually given for having a death penalty."	Liebman et al. examined the judicial review of 4,578 capital cases between 1973 and 1995. Capital cases are more thoroughly reviewed than cases without any death penalty. The added scrutiny reveals serious, reversible errors in the majority of capital sentences in the 23-year period. A portion of these were found innocent of the capital offense. Liebman et al. found incompetent legal defense and Brady violations as two key reversible errors. The study found similarly high error rates reversing capital cases convictions across the states reviewed, ranging from 52% to 70% or higher. The national average or reversed convictions in all capital cases from 1973 to 1995 reached 68%.

TABLE for Poveda's study: Self-reported denial of convicted crime

using 2000 criminal justice data

Convicted offense	"Did not commit"
Rape	37.7%
Sex offense (not rape)	26.9%
Murder	17.5%
Weapons	13.4%
Assault	12.8%
Robbery	11.5%
Forgery	9.9%
Burglary	9.0%
Drug sale	8.1%
Drug possession	5.2%
ALL OFFENSES	15.4%

Applied to relevant populations in the U.S.

Using available corrections population data, the table below applies these scholarly estimates to affected populations in the U.S. to appreciate the size of the issue. Although applying each rate equally to each of these populations introduces significant statistical error, the table is offered less to provide specific numbers and more to demonstrate the approximated prevalence and incidence of wrongful convictions.

Prevalence

Prevalence indicates the overall occurrence (of wrongful convictions) in a given felony convicted population. For each of these populations segments, the given rate is divided by the given population to express the apparent prevalence of wrongful convictions in the U.S.

• P1 = 2.2 million prison population
• P2 = 6.9 million custody population (includes jails, detention centers, probation, parole)
• P3 = 14.5 million felony conviction population (typically with rights-limiting collateral consequences of criminal conviction)
• P4 = 19 million felony record population (also limited by an array of collateral consequences of criminal conviction)

Incidence

Incidence is the number of occurrences within a given time period, often reported in the literature as the number of cases per 100,000 per year. To express the apparent incidence of wrongful convictions in the U.S. overall, the given rate is divided by the number of convictions per year.

• I1 = 1.1 million felony convictions per year
• I2 = The 70% proportion of felony convictions that result in some form of incarceration

Rank	Estimate			Prevalence				Incidence
	Estimated rate	Author(s)	Published date	P1 population	P2 population	P3 population	P4 population	I1 per year	I2 per year
1	0.0016%	Hoffman (low end)	2007	35	110	232	304	18	12
2	0.016%	Cassell (low end)	2018	352	1,104	2,320	3,040	176	123
3	0.027%	Scalia (citing Marquis)	2006	594	1,863	3,915	5,130	297	208
4	0.062%	Cassell (high end)	2018	1,364	4,278	8,990	11,780	682	477
5	0.5%	Ramsey & Frank; Zalman (low end)	2007; 2012	11,000	34,500	72,500	95,000	5,500	3,850
6	1%	Zalman (high end)	2012	22,000	69,000	145,000	190,000	11,000	7,700
7	1.95%	Hoffman (high end)	2007	42,900	134,550	282,750	370,500	21,450	15,015
8	2.3%	Gross & O'Brien	2008	50,600	158,700	333,500	437,000	25,300	17,710
9	3%	Ramsey & Frank (high end)	2007	66,000	207,000	435,000	570,000	33,000	23,100
10	3.3%	Risinger (low end)	2007	72,600	227,700	478,500	627,000	36,300	25,410
11	4.1%	Gross, O'Brien, Hu, & Kennedy	2014	90,200	282,900	594,500	779,000	45,100	31,570
12	5.0%	Risinger (high); Roman (low)	2007; 2012	110,000	345,000	725,000	950,000	55,000	38,500
13	6%	Loeffler et al.	2018	132,000	414,000	870,000	1,140,000	66,000	46,200
14	11.6%	Walsh et al.	2017	255,200	800,400	1,682,200	2,204,000	127,000	89,320
15	15%	Roman et al. (high end)	2012	330,000	1,035,000	2,175,000	2,850,000	165,000	115,500
16	15.4%	Poveda (overall average)	2001	338,000	1,062,600	2,233,800	2,926,000	169,400	118,580

Unexonerated

The wrongly convicted not yet officially exonerated are aptly called the unexonerated. The lower estimated rates suggests the only unexonerated remaining are not factually innocent. The larger estimated rates suggests the bulk who are factually innocent are among thousands if not millions of these "unexonerated".

Among the 55,000 letters seeking help received by the Innocence Project's first 25 years only a small margin can receive assistance. This doesn't include the countless letters sent to other innocence movement entities. Innocence projects employ a type of triage to prioritize their limited resources. So they tend to support those facing the greatest threat to their liberties, starting with death row cases.

Misdemeanor exonerations account for about 2% of known exonerations, while making up 80% of all criminal convictions in the U.S. The countless wrongly convicted who have already served their sentence receive the least effort. The high volume of potentially unexonerated suggest if Innocence Projects legitimately require more resources to process an overwhelming volume of viable innocence claims.

This table illustrates subtracts the known number of official exonerations from the figures in the table above. The results suggest whether all of the actually innocence are being cleared (and dipping into mere legal exonerations) or if current efforts are barely scratching the surface.

NRE = National Registry of Exonerations's latest count of known official exonerations, which stands around 2,500 at the time of this writing.

Estimated rate	P1 - NRE	Percent cleared	P2 - NRE	Percent cleared	P3 - NRE	Percent cleared	P4 - NRE	Percent cleared
0.0016%	–	–	–	–	–	–	–	–
0.016%	–	–	–	–	–	–	1,660	151%
0.027%	–	–	–	–	1,415	177%	2,630	95.1%
0.062%	–	–	1,178	141%	6,490	38.5%	9,280	26.9%
0.5%	8,500	29.4%	32,000	7.81%	70,000	3.57%	92,500	2.70%
1%	19,500	12.82%	66,500	3.76%	142,500	1.75%	187,500	1.33%
1.95%	40,400	6.19%	132,050	1.89%	280,250	0.89%	368,000	0.68%
2.3%	48,100	5.20%	156,200	1.60%	331,000	0.76%	434,500	0.58%
3%	63,500	3.94%	404,500	1.22%	432,500	0.58%	567,500	0.44%
3.3%	70,100	3.57%	225,200	1.11%	476,000	0.53%	624,500	0.40%
4.1%	87,700	2.85%	280,400	0.89%	592,000	0.42%	776,500	0.32%
5.0%	107,500	2.33%	342,500	0.73%	722,500	0.35%	947,500	0.26%
6%	129,500	1.93%	411,500	0.61%	867,500	0.29%	1,137,500	0.22%
11.6%	252,700	0.99%	797,900	0.31%	1,679,500	0.15%	2,201,500	0.11%
15%	327,500	0.76%	1,032,500	0.242%	2,172,500	0.12%	2,847,500	0.09%
15.4%	336,300	0.74%	1,060,100	0.24%	2,230,500	0.117%	2,923,500	0.09%

Contrasted to the latest number of known exonerations, this table suggests the gravity of the problem. As one of these scholars put it in an opinion piece for The Washington Post, "We know without doubt that the vast majority of innocent defendants who are [wrongly] convicted of crimes are never identified and cleared."

Debating the wrongful conviction rate can be merely academic for the wrongly convicted themselves with little if any hope for exoneration. For those negatively impacted by such wrongful convictions, one is already one too many.

See also

• Conviction rate
• Innocence Project
• List of wrongful convictions in the United States
• Miscarriage of justice
• United States incarceration rate

Further reading

Articles

• Borchard, E. M. (1913). European systems of state indemnity for errors of criminal justice, 3 J. Am. Inst. Crim. L. & Criminology 684
• Connors, E.; Lundregan, T.; Miller, N.; MeEwan, T. (1996). Convicted by juries, exonerated by science: Case studies in the use of DNA evidence to establish innocence after trial. National Institute of Justice, U.S. Dept of Justice Office of Justice Programs.
• Drizin, S. A.; Leo, R. A. (2008). The problem of false confessions in the post-DNA world, 82 N.C. L. Rev. 891, 901-07
• Garrett, Brandon (2008). Judging innocence. Colum L. Rev. 108:55-142.
• Gould, J.B.; Carrano, J.; Leo, R.; Hail-Jares, K. (2014). Predicting Erroneous Convictions. 99 Iowa L. Rev. 471 (2013-2014)
• Gross, S. R.; O'Brien, B. (2010). Reply to Richard A. Leo and John. B. Gould. Ohio St. J. Crim. L. 8,2: 273-6 Authors respond to criticism of their methodology.
• Lachman, P. (2019) "Diverging Models of Post Conviction Review and Estimates of the Rate of Wrongful Conviction in Serious Person Crimes." Paper presented at the annual meeting of the ASC Annual Meeting, San Francisco Marriott, San Francisco, California
• Leo, R. A. Leo (2005). Rethinking the study of miscarriages of justice: Developing a criminology of wrongful convictions, 21 J.Contemp.Crim.Just. 201, 203
• Leo, R. A.; Gould, J. B. (2009). Studying wrongful convictions: Learning from social science. Ohio St. Journ of Crim. Law, 7:7.
• Leo, R. A.; Ofshe, R. J. (1998). The Consequences of False Confessions: Deprivations of Liberty and Miscarriages of Justice in the Age of Psychological Interrogation, 88 J. Crim. L. & Criminology 429
• McCloskey, J. (1989). Commentary: Convicting the innocent. Criminal Justice Ethics, 8:1. As the director of Centurion Ministries, McCloskey asserts, "it is my perception that at least 10 percent of those convicted of serious and violent crimes are completely innocent."
• Simon, D. (2006). Are wrongful convictions episodic or epidemic?. Paper Presented at the Annual Meeting of the Law and Society Association (July 7-9, 2006).
• Zalman, M.; Smith, B.; Kiger, A. (2008). Officials' Estimates of the Incidence of "Actual Innocence" Convictions. Justice Quarterly , 25:1, 72-100. Survey of MI justice system officials to replicate Ramsey & Frank (2007) finding of a .5-3% rate.

Books

• Edwin Borchard (1932). Convicting the Innocent: Sixty-Five Actual Errors of Criminal Justice. New York: Garden City Publishing Company, Inc. ISBN: 1452862427
• Barry Scheck, Peter Neufeld & Jim Dwyer (2000). Actual Innocence: Five Days to Execution And Other Dispatches From The Wrongly Convicted. New York: Doubleday. ISBN: 0-385-49341-X

External links

• National Registry of Exonerations, a registry of exonerations in the United States since 1989; a joint project of the University of Michigan Law School and Northwestern University School of Law

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