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Back to Archives | Back to October 2010 Contents 

When the Guilty Walk Free: The Role of Police in Preventing Wrongful Convictions

By Peter Modaferri, Chief of Detectives, Rockland County District Attorney’s Office, New City, New York; Patricia Robinson, PhD, Executive Dean for Criminal Justice, Fox Valley Technical College, Appleton, Wisconsin; and Phyllis McDonald, EdD, Director of Research and Associate Professor, Division of Public Leadership, Johns Hopkins University, Baltimore, Maryland

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t does not take long on the job for a rookie police officer to realize that hardly anyone admits guilt, even when caught redhanded. Sometimes a skillful interrogator can elicit a confession, but just as often—maybe more often—suspects continue to maintain their innocence right through conviction and sentencing, even if they take plea bargains. Most of the time, actual guilt is not really in question. Regardless of whether the suspect admits it, the police, the prosecutor, and the court get it right. Guilty people go to prison.

But what about when the criminal justice system gets it wrong? The use of DNA, in particular, has demonstrated that, sometimes, law enforcement and the courts identify an innocent person as guilty. The Innocence Project, a national litigation and public policy organization dedicated to exonerating wrongfully convicted people through DNA testing and reforming the criminal justice system to prevent future injustice, reports that so far, DNA evidence has exonerated more than 250 people in 34 states who were wrongly convicted. Seventeen of those had served time on death row.1 Given that DNA is not available in all cases and given limited resources for researching and pursuing potential wrongful convictions, the number of people in prison who are actually innocent could be considerably higher. According to the Bureau of Justice Statistics, more than 1.5 million people are incarcerated in U.S. state and federal prisons, with another million held in jails.2 Even if the criminal justice system is right 99 percent of the time, that would still mean that more than 15,000 innocents remain behind prison bars, while the real criminals walk free.

Will the U.S. criminal justice system ever be able to achieve 100 percent accuracy? Of course not. The system is made up of humans, and humans will never achieve perfection. But that does not mean its members should not do everything possible to prevent wrongful convictions because the consequences are so severe—for the wrongly imprisoned, for the community, and for the police.

Many of those exonerated by DNA evidence had no prior criminal history at all at the time of arrest.3 An example is Dwayne Dail, who was convicted in 1989 of raping a 12-year-old girl. He spent the next 18 years in prison until DNA recovered from the child’s nightgown—evidence that by policy should have been destroyed years earlier—indicated that someone else committed the crime. Prior to his conviction, Dail’s only brush with the law had been a speeding ticket. He was 19 when the crime was committed. He emerged from prison at age 39. The years in between, when most people are building families and establishing careers, are forever lost.

The damage is not limited to the wrongly convicted. Whenever an innocent person is wrongly convicted of a crime, the real perpetrator remains free. In some cases, these individuals go on to commit other crimes—sometimes horrific ones. The Innocence Project has documented 47 rapes and 19 murders committed by people who remained at large because someone else had been wrongly convicted of their crimes.4

Law enforcement suffers as well. When something goes awry in the criminal justice system, the public is quick to blame the police. Law enforcement is highly visible and readily identified. For the police to be effective, law enforcement professionals must earn and keep the trust of their communities. To do so is not easy; in fact, a recent article in the Community Oriented Policing Services office e-newsletter reports that despite demonstrable improvements in police performance and professionalism, public confidence in the police has remained stuck at or below 60 percent for the last 30 years.5 Wrongful convictions, whether or not they result from police conduct, erode that trust and damage law enforcement’s reputation.

Rarely do wrongful convictions result from intentional wrongdoing on the part of police or prosecutors, although some have. Indeed, the vast majority have followed clear, convincing testimony by sincere eyewitnesses, which, quite simply, turned out to be inaccurate. The conviction of Dwayne Dail, referenced earlier, was just such a case. The police had a victim who never wavered in her identification of Dail as the perpetrator. DNA testing was not available in 1987. Hairs collected from the scene were microscopically consistent with Dail’s, according to expert testimony. Given all that, a conviction seems reasonable, although clearly it was incorrect.

How It Happens

Through an examination of a criminal justice system process chart, it is easy to see opportunities along the way where a wrongful conviction can occur if those involved are not sufficiently conscientious.

1. First responder. Opportunities for error arise if the first responder does not respond quickly enough, does not protect evidence, does not take identifications of all witnesses, does not record information correctly, or does not pass all information along to detectives.

2. Investigator. Opportunities for error arise if the investigator does not preserve all evidence, does not submit all evidence for analysis, misinterprets evidence, does not interview all possible witnesses, or does not submit all analyzed evidence to the prosecutor.

3. Crime lab. Opportunities for error arise if individuals at the crime lab do not analyze evidence accurately or correctly; do not provide the investigator with all of the results of the analysis; do not preserve evidence sufficiently, leading to errors in interpretation; do not analyze evidence quickly enough, and deterioration occurs; or do not check for false negatives or false positives.

4. Prosecution. Opportunities for error arise if the prosecution does not accept all evidence, including witness statements offered; misinterprets evidence and witness statements deliberately or accidentally; or does not act in a timely manner.

5. Defense attorney. Opportunities for error are the same as those for the prosecution.

6. Jury. Opportunities for error arise if the jury allows hidden agendas to prevail over judgment or forgets to consider some of the evidence presented.

7. Judge. Opportunities for error arise if the judge has preconceived notions about the offender’s guilt or innocence or does not conduct the trial according to protocol.

The major causes of the first 225 exonerations cited on the Innocence Project website fall into four categories (see figure 1).6

Many of these problems can be mitigated by better procedures and investigative protocols, and indeed, efforts are under way to develop best practices in these areas. An example is the use of double-blind, sequential lineups, in which the administrator does not know which person is the suspect and in which individuals are presented one at a time, in succession, rather than all at once. Research shows that when subjects are presented all at once, witnesses tend to compare the subjects to each other rather than to their memories of the perpetrator. Thus they tend to pick the one who most resembles the perpetrator within that group of people. On the other hand, when subjects are presented one at a time, witnesses tend to compare each one to their memories of the perpetrator, and the incidence of false positives is much reduced.7

The Role of Police Image

As law enforcement officers examine their professional practices and seek ways to reduce the incidence of wrongful convictions, they must consider one more potential contributing factor: their view of themselves and of their role. If a sample of the population (including law enforcement) was asked about the role of the police with respect to crime, responses would probably resemble the following:

  • To solve crimes

  • To catch “bad guys”

  • To gather facts and information

  • To arrest the perpetrator

All of these are accurate descriptions and legitimate roles for the police, but they are not equivalent. For example, the role of catcher of criminals is much narrower than the role of gatherer of facts. The two are not incompatible—indeed, unless the officer witnesses the crime in progress, catching the perpetrator will require gathering facts. But if officers view their jobs as “to catch bad guys” by fighting crime, arresting suspects, clearing cases, and so on, then once officers have identified viable suspects, it would be reasonable (and almost irresistible) that they focus their efforts on building cases against those suspects and later assist the prosecution in any way they legally can to obtain convictions.

On the other hand, if officers view their jobs as “to gather facts and information,” then they will be equally interested in all facts relevant to the crimes they are investigating; they will be just as interested in excluding the innocent as in finding the guilty.

If one surveyed police detectives across the country as to which role they view as primary, many, and perhaps even most, would opt for “to gather facts and information.” Yet a number of influences in the political world and society at large tend to push investigators to be catchers of bad guys rather than neutral fact finders. These include

  • limited resources available for conducting investigations;

  • political pressure to solve crimes and make an arrest quickly, especially in highprofile crimes;

  • measuring investigative performance by numbers of cases closed;

  • TV and movie images of police as highaction criminal catchers;

  • police trainers who promote the warrior image, which may enhance officer safety but also clearly favors the bad-guy catcher role over the neutral fact finder role; and

  • equipment manufacturers and vendors who promote the image of police as elite crime fighters (for example, describing all products, even socks, as “tactical”).8

From the standpoint of reducing wrongful convictions, the image of police as criminal catchers carries with it a serious danger: increased potential for investigational bias—the unconscious tendency to look for facts that support a theory and ignore ones that undermine it. Good investigative protocols can reduce the effect of investigational bias, but they cannot entirely eliminate it, in part because it is both unintentional and unconscious.

What Can Be Done

Law enforcement professionals must confront and address their part in the processes that result in wrongful convictions. Certainly, they already have safeguards in place against intentional misconduct. But as noted, most of the problem stems not from intentional misconduct, but rather from flawed practices. What can police executives do to minimize the possibility of a wrongful conviction taking place? As organization leaders, they set the tone for the entire operation. Their words—and, more importantly, their actions—convey their expectations and values. Here are five concrete steps police executives can take:

1. Stay abreast of research and improvements in investigative protocols. Incorporate best practices into the agency’s way of doing business. Recently, a number of states have implemented new protocols for eyewitness identification, recording of interrogations, and so on.9

2. By policy and practice, make exonerating the innocent equally important as identifying and arresting a suspect. Doing so may require additional resources. Fight for those resources: the long-term cost of a wrongful conviction will be much higher, both in dollars and in lost confidence.

3. Reward quality over quantity of investigation. Encourage thoroughness. Insist that investigators run down every lead and resist the urge to cut corners. Avoid measuring performance on number of cases closed. Hold front-line supervisors accountable for ensuring comprehensive investigation.

4. Resist political pressure to solve the case quickly or make an arrest prematurely. The police executive’s job is to take the heat so officers can do their jobs correctly.

5. Keep officers focused on their role of unbiased investigators. The job of the police is to investigate crimes—in other words, to find out what happened. The police must remain impartial; the moment they slip into advocacy, their effectiveness is compromised because their testimony becomes suspect. Avoid measuring performance on the basis of convictions.

Every police officer swears an oath to uphold the U.S. Constitution. In a very real way, the police embody the rule of law. By any measure, a wrongful conviction represents a miscarriage of justice—and one with devastating consequences. Law enforcement professionals must be vigilant in enforcing the law by seeking out and arresting wrongdoers, but they must be equally vigilant in protecting the innocent and guaranteeing fair and equitable treatment for all. ■


1“Facts on Post-Conviction DNA Exonerations,” the Innocence Project, August 20, 2010).
2William J. Sobel et al., “Prisoners in 2008,” NCJ 228417, December 8, 2009, Bureau of Justice Statistics, (accessed August 20, 2010); “Probation and Parole in the United States, 2008,” NCJ 228230, December 8, 2009, Bureau of Justice Statistics, (accessed August 20, 2010); and “Key Facts at a Glance,” Bureau of Justice Statistics, (accessed August 20, 2010).
3“About Us: FAQs,” the Innocence Project, (accessed August 20, 2010).
4“Innocence by the Numbers: Real Perpetrators,” The Innocence Project in Print 3, no. 2 (2007): 22, (accessed August 20, 2010).
5Tom R. Tyler, in collaboration with Albert A. Pearsall III, “The Paradox of American Policing: Performance without Legitimacy,” Community Policing Dispatch, 3 (July 2010), (accessed August 20, 2010).
6“The Causes of Wrongful Conviction,” the Innocence Project, (accessed August 20, 2010).
7“Eyewitness Identification Reform,” the Innocence Project, August 20, 2010).
8See (accessed August 20, 2010).
9For specific examples, model policies, and resources, see “Fix the System: Model Legislation,” the Innocence Project, (accessed August 20, 2010).

Please cite as:

Peter Modaferri, Patricia Robinson, and Phyllis McDonald, "When the Guilty Walk Free: The Role of Police in Preventing Wrongful Convictions," The Police Chief 77 (October 2010): 34–37, (insert access date).



From The Police Chief, vol. 77, no. 10, October 2010. Copyright held by the International Association of Chiefs of Police, 515 North Washington Street, Alexandria, VA 22314 USA.

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