Academic journal article Harvard Journal of Law & Technology

The Algorithm Says You Did It: The Use of Black Box Algorithms to Analyze Complex DNA Evidence

Academic journal article Harvard Journal of Law & Technology

The Algorithm Says You Did It: The Use of Black Box Algorithms to Analyze Complex DNA Evidence

Article excerpt

                    TABLE OF CONTENTS    I. INTRODUCTION                                             275  II. BACKGROUND                                               276      A. The Science of Complex DNA Mixtures                   276      B. The Unreliability of Previous Methods                 279      C. The Development of Algorithmic Analytic Techniques    281      D. TrueAllele                                            282 III. USAGE IN THE CRIMINAL JUSTICE SYSTEM                     283      A. The First Case: Commonwealth v. Foley                 283      B. Subsequent Unsuccessful Challenges to the Use of DNA         Analysis Algorithms                                   286      C. Use in Exoneration Cases                              287  IV. CONCERNS AND CRITICISMS                                  288      A. Unestablished Scientific Validity                     288      B. Lack of Transparency                                  291   V. POTENTIAL RESPONSES                                      295 


DNA evidence has grown to be widely accepted as reliable proof of an individual's innocence or guilt. (1) Yet, despite the perception of DNA evidence as definitive proof, when DNA evidence involves complex mixtures of multiple individuals' DNA, the science is not as simple as it appears on television. Complex DNA samples are not as straightforward and objective to analyze as simple DNA samples, leaving substantial room for error and variability. (2) Commonly used techniques for analyzing and interpreting complex DNA mixtures have proven unreliable, creating concerns about the potential for improper prosecutions and convictions. (3)

To address the problems of unreliability associated with the subjective techniques typically used to interpret complex DNA mixture results, a number of companies and organizations are working to develop algorithmic systems to interpret the results of analyses of complex DNA mixtures. (4) Unfortunately, these algorithmic programs have problems of their own. Multiple parties have raised concerns about the reliability and accuracy of the algorithmic programs, questioning their scientific validity, and the lack of transparency surrounding the algorithms and their use. (5) The technologies that were intended to solve the problems associated with subjective interpretations of complex DNA mixture analyses have instead opened the door to a whole new set of problems that must be resolved.

Part II of this Note describes the science behind simple and complex DNA mixture analyses, the troubles with subjective analytic techniques, and the background of TrueAllele and related DNA analysis technologies. Part III explores how these technologies have been used in the criminal justice system for both exoneration and conviction, including how courts have ruled in response to challenges to their use. Part IV evaluates criticisms of the use of algorithmic DNA analysis technologies in the criminal justice system, including concerns about their scientific validity and the lack of transparency. Finally, Part V discusses potential responses to these criticisms.


A. The Science of Complex DNA Mixtures

DNA evidence has long been upheld as the "gold standard" for forensic science. (6) Indeed, the public views DNA evidence as extremely reliable and accurate. According to a 2005 poll conducted by Gallup, 85% of Americans consider DNA evidence to be "very or completely reliable." (7) In multiple studies, researchers have found that jurors believe DNA evidence is more than 90% accurate. (8) Unfortunately, that perceived certainty glosses over much of the complexity surrounding some types of DNA evidence.

The science surrounding the analysis and interpretation of DNA evidence has evolved and grown over time. (9) Most DNA analysis for forensic purposes involves samples from only one or two individuals. (10) Analyses of DNA samples that come from a single individual (single-source samples) or from a simple mixture of two individuals (simple-mixture samples) have been well studied and thoroughly tested, and, according to the President's Council of Advisors on Science and Technology ("PCAST"), they are generally considered to be "objective method[s] in which the laboratory protocols are precisely defined and the interpretation involves little to no human judgment. …

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