A Summary of the Columbia University Study by Prof. James S. Liebman


A Summary of the Columbia University Study by Prof. James S. Liebman
by the Death Penalty Information Center

The Study:

This is a statistical study of capital cases funded by the Columbia University School of Law. The study was conducted by Professor James S. Liebman of Columbia University School of Law, Professor Jeffrey Fagan of Joseph Mailman School of Public Health and Valerie West, a Doctoral Candidate in the Department of Sociology, New York University.

The report examined 5,760 capital cases between 1973 and 1995 and concludes that American capital sentences are persistently and systematically fraught with error that seriously undermines their reliability. The report reveals that serious error has reached epidemic proportions in capital cases. More than two out of every three capital judgments reviewed by the courts during the 23 year study period were found to be seriously flawed.

Central Findings:

- Nationally the overall rate of prejudicial error in capital cases was 68% - i.e., courts found serious reversible error in nearly 7 out of 10 capital cases that were fully reviewed during the study period.

- Capital trials produce so many mistakes that it takes three judicial inspections to catch them, leaving doubt whether we do catch them all. After state courts threw out 47% of death sentences due to serious flaws, a later federal review found "serious error" (error undermining the reliability of the outcome) in 40% of the remaining sentences.

- Of the 2,370 death sentences thrown out due to serious error, 90% were overturned by state judges, many of whom were the very judges who imposed the death sentence in the first place. However, a substantial number of the capital judgments they let through to the federal stage were still seriously flawed.

- The most common errors (prompting a majority of reversals at the state post-conviction stage) were (a) incompetent defense lawyers who failed to look for or recognize important evidence of innocence or mitigating factors; and (b) police or prosecutors who suppressed evidence.

- High error rates put people at risk of wrongful execution. 82% of the people whose capital judgments were overturned by state post-conviction courts due to serious error were found to deserve a sentence less than death when the errors were cured on retrial. 7% were found to be innocent of the capital crime.

- The capital review procedure took a national average of 9 years from death sentence to the last inspection and execution. By the end of the study period, the average time needed to make sure death verdicts were free of serious error had risen to 11 years.

- As a result of high error rates, and resulting high reversal rates and lengthy review of procedures, fewer than 5% of all death sentences imposed during the 23-year period between 1973 and 1995 were carried out in that period.

- High error rates exist across the country. Over 90% of American death-sentencing states have overall error rates of 52% or higher. Three-fifths have error rates of 70% or higher.

- Illinois (which announced a moratorium on all executions) does not produce an unusual number of faulty death sentences. The overall rate of serious error found in Illinois capital sentences (66%) is slightly lower than the national average (68%).

Implications of Central Findings

- Capital trials and sentences cost more than non-capital ones. The error detection system all this capital error requires is itself a huge expense, apparently millions of dollars per case.

- Many of the resources consumed by the capital system do not help to obtain the valid death sentences that the majority support. Large amounts of resources are being wasted on cases that should never have been capital in the first place.

- This much error and the time taken to cure it impose terrible costs on taxpayers, victims' families, the judicial system and the wrongly condemned. It also renders unattainable the finality, retribution and deterrence that are the reasons often given for having a death penalty.

- When the condemned person turns out to be innocent the costs are immeasurable; to the wrongly convicted person and his or her family; to the family of the victim whose search for justice and closure has been in vain; to later victims whose lives are threatened or taken because the real killer is still at large; to the public whose confidence in the legal system is shaken; and to the wrongly executed, should the mistake not be caught in time.


The study shows a capital punishment system collapsing under the weight of its own mistakes. If one measures the "success" of the death penalty system by the amount of capital sentences which result in executions then this 23-year-study shows that the system is not a success, and is not even minimally rational.

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