title: Differential reporting of mixed DNA profiles and its impact on jurists' evaluation of evidence. An international analysis.
abstract: While DNA analysis is considered by many the gold standard in forensic science, there is ample room for variation in interpretation and reporting. This seems especially the case when working with (complex) mixed DNA profiles. Two consecutive studies on differential DNA reporting were conducted. In Study 1, we first examined type and magnitude of differences when forensic DNA experts across institutes and jurisdictions are handed an identical forensic case with mixed profiles. In Study 2, we explore the impact of the observed differential reporting on jurists' evaluation of the DNA evidence. 19 DNA expert reports from forensic institutes across Western jurisdictions were obtained. Differences between the reports were many and include extensiveness of the reports, explanations of technical issues, use of explanatory appendices, level of reporting, use of context information, and, most markedly, type and substantive content of the conclusions. In Study 2, a group of criminal law students judged a selection of these reports in a quasi experimental study design. Findings show that these differing reports have quite different evidentiary value for jurists, depending on which expert authored the report. It is argued that the impact of differential reporting on jurists' evaluation was so fundamental and substantive that it is seems reasonable to claim that in an actual court case it could make the difference between acquittal and conviction.
authors.affiliation: Leiden University, Faculty of Law, Institute for Criminal Law and Criminology, Steenschuur 25, NL-2311ES Leiden, The Netherlands. Electronic address: jdekeijser@law.leidenuniv.nl.
authors.forename: Jan W
authors.initials: JW
authors.lastname: de Keijser
authors.affiliation: NSCR (Netherlands Institute for the Study of Crime and Law Enforcement), De Boelelaan 1077a, NL-1081HV Amsterdam, The Netherlands. Electronic address: mmalsch@nscr.nl.
authors.forename: Marijke
authors.initials: M
authors.lastname: Malsch
authors.affiliation: Leiden University, Faculty of Law, Institute for Criminal Law and Criminology, Steenschuur 25, NL-2311ES Leiden, The Netherlands. Electronic address: eggeluining@gmail.com.
authors.forename: Egge T
authors.initials: ET
authors.lastname: Luining
authors.affiliation: NSCR (Netherlands Institute for the Study of Crime and Law Enforcement), De Boelelaan 1077a, NL-1081HV Amsterdam, The Netherlands. Electronic address: mweulenkranenbarg@nscr.nl.
authors.forename: Marleen
authors.initials: M
authors.lastname: Weulen Kranenbarg
authors.affiliation: Leiden University, Faculty of Law, Institute for Criminal Law and Criminology, Steenschuur 25, NL-2311ES Leiden, The Netherlands. Electronic address: lenssendominique@gmail.com.
authors.forename: Dominique J H M
authors.initials: DJHM
authors.lastname: Lenssen
mesh_terms: D000328:Adult; D001315:Australia; D004247:DNA / Q000235:genetics*; D016172:DNA Fingerprinting / Q000331:legislation & jurisprudence*; D005060:Europe; D005104:Expert Testimony / Q000331:legislation & jurisprudence*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014481:United States
chemical_list: D004247:DNA
keywords: DNA analysis; DNA interpretation; Differential DNA reporting; Evaluation of evidence; Mixed DNA profiles