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Forensic science: a vital role in criminal justice

Forensic science has and continues to play a vital role in the criminal justice system.

April 11, 2017  By Wade Knaap & Jessica Peikny

The first criminalistics laboratory in North America opened its doors in Montreal in 1914. The Laboratoire de recherches médico-légales was the vision and creation of Dr. Wilfrid Derome. Since its humble beginnings, forensic science has evolved into what is arguably the greatest investigative tool available to police, and ultimately a requirement for the criminal courts with many Trier of Facts being reluctant to register conviction without corroborative or supportive forensic evidence.

Forensic science is the application of science to a legal investigation (medicolegal). Advancements within the scientific community continue with new and emerging technologies being introduced at an accelerated rate. It is imperative that these novel techniques, equipment and methodologies are scrutinized or vetted prior to their acceptance within the criminal justice system. Permitting “junk science” to be tendered as evidence diminishes the integrity and importance of all forensic evidence, potentially weakening its significance or evidentiary value. It is therefore incumbent upon the legal system to ensure that scientific evidence meets a standard of excellence before it is introduced into a legal inquiry.

In 2009, the National Academy of Science Report: “Strengthening Forensic Science in the United States: A Path Forward” was published. Often referred to as the NAS report, it examined the status of forensic science in the U.S., offering both positive and negative criticisms in an effort to improve the forensic science disciplines.

The NAS report concluded, “with the exception of nuclear DNA analysis … no forensic method has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source.

Certain forensic disciplines were identified as being particularly flawed: ballistic evidence, fire investigations, and bite mark evidence. Although the report was localized to the U.S., its rippling effect impacts the Canadian criminal judicial system as well. This assessment served as a wake-up call to the forensic science disciplines and has encouraged the community to self-assess its practices, methodologies and conclusions.

Following in the footsteps of the NAS report, in 2016 The Executive Office of the President of the United States – The President’s Council of Advisors on Science and Technology (PCAST), reported on the following topic: Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods.

The PCAST report identified and readdressed two areas of criticism that were highlighted in the earlier NAS report. PCAST concluded two major gaps:

  1. There isn’t enough clarity regarding the reliability and validity standards for forensic methodology
  2. A need to evaluate certain disciplines to determine whether they have been scientifically established as a valid and reliable means of comparison evidence.

The NAS and PCAST reports are often referenced in court by defence counsel in an effort to discredit forensic science and limit its acceptance or evidentiary weight. Although many of the arguments highlighted in these reports are unwarranted or unfounded, nevertheless they do create issues for practitioners tendering evidence in court.

Since the early 1990s, American and international forensic science laboratories and practitioners collaborated in Scientific Working Groups (SWGs) to improve discipline best practices and create consensus standards or guidelines. These working groups were dedicated to individual forensic disciplines across all platforms. (Example – SWGFAST: Scientific Working Group on Friction Ridge Analysis, Study and Technology). The scientific working groups were supported by the US Department of Justice and continued to function in an advisory capacity, providing guidance and validation to forensic science disciplines.
In 2014, the SWGs were restructured under the National Institute of Standards and Technology (NIST), a division of the US Department of Commerce. NIST, along with professionals within the forensic science community, established the new Organization of Scientific Area Committees (OSAC). The mandate of this organization is to coordinate the development of standards and guidelines for each of the disciplines within the forensic science community and to improve the quality and consistency of work performed by the investigators and professionals in the field.

Notwithstanding the significance of these reports, forensic investigators need to be diligent and aware of these and other trending topics that may affect their ability to tender evidence in court. Many of these current issues can be attributed to case law, particularly:

  • Daubert v. Merrell Dow Phamaceuticals, 509 U.S. 579 (1993) – (U.S.), or
  • R. v. Mohan, (1994) 2 SCR 9 – (Canada)

These two judicial decisions form the foundation and threshold for the admissibility of any scientific evidence in court:

  1. Whether the theory and technique have been tested;
  2. Whether the theory and technique have been subjected to peer review and publication;
  3. Known or potential error rate;
  4. Existence and maintenance of standards; and
  5. General acceptance within relevant scientific community.

It should be duly noted that forensic science remains a vital component of the Canadian criminal justice system, and practitioners remain dedicated to ensuring it responds with due diligence in maintaining the current standard of excellence.

Wade Knaap is a part-time faculty member with the University of Toronto (Mississauga) Forensic Science Program and a retired Toronto Police forensic identification officer. He can be reached at:

Jessica Piekny is a Crime Scene Support Technician with the Toronto Police Service Forensic Identification Service.

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