G. Police Investigation
At its best, police investigation is the patient, systematic, and dispassionate search for, discovery of, and evaluation of all relevant facts of a suspected crime. The goal is to establish whether a crime was committed and to identify and apprehend the perpetrator(s). This complex and sensitive task requires solid understanding of criminal law, extensive knowledge about criminal behavior and crime patterns, complete familiarity with the methods of evidence collection and analysis of forensic evidence, skill in interviewing witnesses, and good analytic and writing abilities.
Although it is inevitable that some crimes will not be solved and some innocent suspects will be mistakenly identified, several factors increase the probability of error. One is tunnel vision, which in fact affects all people and all criminal justice system participants. This term encompasses well-established psychological cognitive mechanisms such as confirmation bias, or the human tendency to seek and interpret new information in ways that confirm preconceptions and avoid information and interpretations that contradict prior beliefs. When applied to police investigation, tunnel vision is the tendency to focus on the first suspect and then to select and filter evidence that builds a case for guilt, while ignoring or suppressing exculpatory evidence. Tunnel vision is an unconscious or “natural” and entirely nonmalicious process. However, its worst effects are amplified by aspects of police investigation such as the nature of interrogation, discussed earlier.
Another problem is the nature of the police investigation report. This document is tremendously important, because in most cases there is limited or no investigation by the defense (in large part because of severely limited funds) and so the police case, found in the report, becomes the official facts in the case. The police report is relied on heavily by the prosecutor in deciding whether and what crimes to charge, by the magistrate in setting bail and ordering detention for psychological evaluation, and even by defense attorneys who do not independently investigate their client’s cases for plea bargaining and trial purposes. It is the basis on which an officer testifies at trial and can influence sentencing decisions.
In contrast to European countries, where police investigation is supervised by investigative magistrates who are well-trained judicial officers in national ministries (departments) of justice, American police investigation (aside from federal cases) is almost entirely under the control of local police departments. European police reports are highly detailed, part of the official dossier, and geared to ascertaining the truth; American reports are internal documents that serve functions other than informing the prosecution, such as evaluating personnel. Police are not specifically trained to include exculpatory information in reports, despite orders to include “all” information. Severe time pressure makes it difficult for police to write comprehensive reports, and police are trained to not report information that could lead to civil suits against themselves or their departments. Studies indicate that police reports do not normally contain exculpatory facts, and in fact are often deficient in reporting inculpatory facts, to the discomfit of prosecutors. A few cases have uncovered deliberate fabrication and the exclusion of exculpatory evidence in police reports that framed innocent suspects. It is not known how pervasive these behaviors are. What is probably more common is for overworked police officers to focus on the initial suspect and enter facts in their field notes and follow-up reports that confirm their initial suspicion. Once written, there is no regular procedure to incorporate contradictory or exculpatory evidence in police reports.
H. Other Causes, Root Causes
This list of wrongful conviction causes is not comprehensive. Race may play a part, either by blatant discrimination, subtle bias, or as a result of the weaknesses of cross-racial identification. This last results not from bias but from familiarity that allows people to see subtle facial features among people with whom they are familiar. A disproportionate number of wrongful convictions have occurred against African American men convicted of raping white women.
The death penalty may also generate a higher proportion of wrongful convictions. Police, under extreme pressure to solve capital murders, rely on marginal evidence to fasten their attention on suspects. The American war on crime and its hyperimprisonment (at five to eight times the levels found in other advanced democracies with comparable crime levels except for homicide) has created a proprosecution atmosphere, leading police, prosecutors, judges, juries, and appellate courts away from balanced decision making, probably resulting in more miscarriages of justice.
In addition, pervasive root causes of wrongful convictions exist. One, discussed earlier, is tunnel vision. Another is the lack of resources for all actors (police, prosecutors, and courts, as well as defense lawyers). This creates extreme pressure to investigate cases within limited time periods. Overlapping with pressure is the system’s normal bureaucratic functioning and production demands, which channel the work of justice officials into routines that make it difficult to slow case processing for more careful examination where called for. These bureaucratic imperatives are aggravated by structural factors that may be impossible to change. The American governmental and criminal justice system is the most fragmented of any modern nation. There are substantial differences in quality among the 16,000 local police departments and 3,000 prosecutors’ offices in the nation. The election of prosecutors and judges, virtually unheard of anywhere else in the world, injects a level of partisanship into criminal justice that often undermines rational action. These factors may in turn create a culture of impunity among investigators and prosecutors in which errors are seldom restrained and misconduct rarely punished. The adversary system of trial, which imposes a large burden on the defense to counter the prosecution with its own evidence, is fatally flawed when criminal defendants almost never have the ability to independently gather evidence.