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​​Forensic Evidence


​Currently seven states have enacted language to permit changes in science in their respective post conviction relief statutes. The Innocence Project has summarized them.

  • California: Cal Pen Code § 1473.7(b) A writ of habeas corpus may be prosecuted for, but not limited to, the following reasons (1) False evidence that is substantially material or probative on the issue of guilt or punishment was introduced against a person at a hearing or trial relating to the person’s incarceration; (4) A significant dispute has emerged or further developed in the petitioner’s favor regarding expert medical, scientific, or forensic testimony that was introduced at trial and contributed to the conviction, such that it would have more likely than not changed the outcome at trial.

    (e)(1) For purposes of this section, "false evidence" includes opinions of experts that have either been repudiated by the expert who originally provided the opinion at a hearing or trial or that have been undermined by the state of scientific knowledge or later scientific research or technological advances. 

  • Connecticut: Conn. Gen. Stat. § 52-582(b)(1) Such newly discovered evidence in support of a petition for a new trial may include newly discovered forensic scientific evidence that was not discoverable or available at the time of the original trial or original or previous petition for a new trial, as determined by the court under subdivision (2) of this subsection, including that which might undermine any forensic scientific evidence presented at the original trial. (2) The court shall consider whether relevant forensic scientific evidence was not discoverable or available at the time of the original trial based upon a consideration of whether the relevant scientific evidence has changed since the applicable trial date or dates, or date of entry of a plea of guilty or nolo contendere, or the date of the most recent petition under this section.

  • Michigan: Court Rule: MCR 6.502. Motion for Relief. (G)(3)For purposes of subrule (G)(2), "new evidence" includes new scientific evidence. This includes, but is not limited to, shifts in science entailing changes: (a) in a field scientific knowledge, including shifts in scientific consensus; (b) in a testifying expert's own scientific knowledge and opinions; or (c) in a scientific method on which the relevant evidence at trial was based.

  • Nevada: Nev. Rev. Stat. Ann. § 34.930. "Newly discovered evidence" means evidence that was not available to a petitioner at trial or during the resolution by the trial court of any motion to withdraw a guilty plea or motion for new trial and which is material to the determination of the issue of factual innocence, including, without limitation: (3) relevant forensic scientific evidence . . . that undermines materially forensic scientific evidence presented at trial.

  • Texas: Tex. Code Crim. Proc. Art. 11.073 (a) this article applies to relevant scientific evidence that: (2) contradicts scientific evidence relied on by the state at trial.

  • West Virginia: W. Va. Code § 53-4A-1(b)(1) For purposes of this article, and notwithstanding any other provisions of this article, a contention or contentions shall not be deemed to be previously and finally adjudicated when either relevant forensic scientific evidence exists that was not available to be offered by a petitioner at the time of the petitioner’s conviction or which undermines forensic scientific evidence relied on by the state at trial; and there is a reasonable probability there would be a different outcome at trial.

  • Wyoming: Wyo. Stat. § 7-12-402(a) (iv) “Newly discovered evidence” means evidence that was not available to the petitioner at trial or during the resolution by the trial court of any motion to withdraw a guilty plea or motion for new trial and which is relevant to the determination of the issue of factual innocence, including: (C) Relevant forensic scientific evidence that was not available at the time of trial or during the resolution by the trial court of any motion to withdraw a guilty plea or motion for new trial, or that undermines forensic evidence presented at trial. Forensic scientific evidence is to be considered as “undermined” if new research or information exists that repudiates: (I) The foundational validity of the challenged evidenceor testimony. “Foundational validity” means the reliability of the method to be repeatable, reproducible and accurate in a scientific setting; or (II) The applied validity of the method or technique. “Applied validity” means the reliability of the method or technique in practice.

Valena Beety, "Changed Science Writs and State Habeas Relief" - 2020

This article reviews the growth of state-level changed science writs and examines how other states can adopt this tool to review habeas petitions based on scientific evidence. This Article posits that changed science writes both incentivize greater reliability of evidence at trial by creating a process of review, and help to identify wrongful convictions based on inaccurate, misrepresented, or faulty scientific evidence. 

Simon A Cole, Changed Science Statutes: Can Courts Accommodate Accelerating Forensic Scientific and Technological Change?" - 2017

In the past several years, the nation's two most populous states have passed new statutes specifically intended to address the issue of rapidly changing scientific and technological knowledge, perhaps signaling a national trend. This reflection article situates a discussion of these "changed science statutes" within a sociological understanding of the nature of scientific knowledge, exploring the question of what it means for scientific knowledge to "change." It then traces the procedural history of the two cases widely credited with prompting the passage of the statutes and courts' varying interpretations of the statutes. It suggests that, while changed science statutes offer broad potential for redressing the use of impunged science in closed cases, courts have thus far limited their applicability through narrow interpretation of the statutes.

Post-conviction fingerprint/ballistic database access statutes

Although all 50 states have statutes enabling some form of access to post-conviction DNA database searching, only 6 states (Arizona, Arkansas, Idaho, Illinois, Minnesota, and Tennessee) extend that right to other kinds of forensic databases (such as fingerprint and ballistics).

Nine people have been exonerated in part because they were able to conduct post-conviction fingerprint database searches, and Patrick Pursley was exonerated in part because of a post-conviction ballistics database search.

In this op-ed, Registry Director Simon Cole and Innocence Project Co-Founder Barry Scheck argue in favor of a right to post-conviction searching of all forensic databases. They write about that issue, and others, in:

Simon A. Cole & Barry C. Scheck, Fingerprints and Miscarriages of Justice: 'Other' Types of Error and a Post-Conviction Right to Database Searching - 5 July 2018​

General Studies of Forensic Evidence and Wrongful Conviction

Catherine L. Bonventre, Wrongful convictions and forensic science - 18 October 2020

More than 2,600 exonerations have been documented in the United States since 1989. Forensic science—in the form of postconviction DNA testing—has played a critical role in the revelation that wrongful convictions are a problematic feature of criminal justice. Yet, forensic science is also among the many factors—including eyewitness misidentification, false confessions, informants, and more—that are correlates of wrongful convictions. Forensic science contributes to erroneous convictions when analysts provide invalid testimony at trial or when such evidence fails to correct false crime theories. Moreover, while intentional forensic misconduct certainly exists, the effects of confirmation biases may present a greater threat to forensic analyses. The preceding mechanisms and reform efforts are discussed. Read More.

Vanessa Meterko, Strengths and Limitations of Forensic Science: What DNA Exonerations Have Taught Us and Where to Go From Here - December 2016 

The criminal justice system has historically accepted forensic science testimony with great deference and trust. After all, scientists are intellectually curious experts with specialized training who make dispassionate observations about the laws of nature. However, over the past 25 years, post-conviction deoxyribonucleic acid ("DNA") testing has revealed the limitations of scientific evidence by conclusively proving innocence in cases in which forensic analysts had previously presented evidence of guilt. In this way, DNA exoneration cases have prompted a more critical evaluation of forensic science in general. Read more.

Simon A. Cole, “Forensic Science and Miscarriages of Justice” in Gerben Bruinsma & David Weisburd (eds), Encyclopedia of Criminology and Criminal Justice (Springer, 2014), pp. 1763-1773,

The relationship between forensic science and miscarriages of justice is complex and paradoxical. Miscarriages of justice are, in a sense, fundamentally unknowable. Forensic science, in the form of postconviction DNA testing, is the data source of much of the little we do know – and much of what we feel we know most securely – about miscarriages of justice. At the same time, forensic science has emerged from those very data as a significant contributor to miscarriages of justice. Read More.

Simon A. Cole, Forensic Science and Wrongful Convictions: From Exposer to Contributor to Corrector - June 6, 2012

Brandon Garrett's book, Convicting the Innocent, makes a number of important contributions to the scholarly and public discourse on miscarriages of justice. In this essay, I will focus on the contribution that is most related to my own reserarch interests: its contribution to our understanding of the relationship between forensic science and miscarriages of justice. Read more.

Brandon L. Garrett & Peter Neufeld, Invalid Forensic Science Testimony and Wrongful Convictions - March 2009 

This is the first study to explore the forensic science testimony by prosecution experts in the trials of innocent persons, all convicted of serious crimes, who were later exonerated by post-conviction DNA testing. Trial transcripts were sought for all 156 exonerees identified as having trial testimony by forensic analysts, of which 137 were located and reviewed. These trials most commonly included testimony concerning serological analysis and microscopic hair comparison, but some included bite mark, shoe print, soil, fiber, and fingerprint comparisons, and several included DNA testing. Read more.