Double-Blind Sequential Police Lineup Procedures: Toward an Integrated Laboratory and Field Practice Perspective

• NCJ Number: 246939
• Author(s): Nancy K. Steblay
• Date Published: March 2007
• Length: 111 pages
• Grant Number(s): 2004-IJ-CX-0044
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical); Report (Study/Research); Report (Grant Sponsored)

Annotation

This project integrated behavioral data from scientific research, current field experience, and new laboratory investigations in advancing knowledge about best police lineup practice for law enforcement and research communities.

Abstract

The project - which was conducted in Hennepin County, MN, in cooperation with the County Attorney's Office - achieved a successful application of double-blind sequential lineups to street investigations, resulting in the use of double-blind sequential lineups across the county. "Double-blind" means that neither the manager of the lineup nor the witness knows whether a suspect held by the police is in the lineup. This prevents the manager of the lineup from inadvertently or intentionally directing the witness to the suspect, since the manager does not know which person in the lineup is being held by the police. Also, the fact that witnesses know the lineup manager does not know which person in the lineup is being held by police discourages them from seeking coaching from the manager. Sequential administration of a lineup involves presenting lineup photos of persons or actual persons one at a time, so as to reduce side-by-side comparisons. The field data and laboratory test data converged to show increased misidentifications when a witness was allowed to view the lineup more than once. The lab study also showed how reduced lineup size, caused by attrition due to the witness' recognition of filler persons for the lineup, can negatively influence eyewitness identification accuracy. The project included two components: a pilot program of double-blind sequential lineups in Hennepin County and a laboratory investigation of eyewitness memory under revised lineup procedures. These combined data sources produced important new information about successful field practice in eyewitness identification of suspects, as well as scientifically based answers to questions about the effects of specific changes to prescribed lineup protocol. 10 tables and 80 references