This past Monday, the Texas Court of Criminal Appeals officially exonerated Steven Mark Chaney, who was sentenced in 1987 to life in prison for a murder he did not commit. Although he was released after decades of wrongful imprisonment in October 2015, Chaney wasn’t declared “actually innocent” until this past December, a decision ratified by the court on Monday.
Chaney’s conviction more than 30 years ago was based largely on the scientifically indefensible testimony of two forensic dentists “matching” Chaney to a supposed bite mark on the arm of the murder victim. As the tenth anniversary of the 2009 National Forensic Science (NAS) report approaches, the court’s decision to invalidate the use of bite mark analysis in Chaney’s case is especially significant.
In declaring Chaney “actually innocent,” the Texas Court of Criminal Appeals cites extensively from the 2009 NAS report, invalidating the use of bite mark analysis in his conviction and concluding that such testimony would not be admissible evidence today. Indeed, the Texas court found that “the body of scientific knowledge underlying the field of bitemark comparisons evolved in a way that discredits almost all the probabilistic bitemark evidence at trial,” and went on to find that the new “bitemark evidence, which once appeared proof positive of . . . Chaney’s guilt, no longer proves anything.”
As a result of Chaney’s case, the Texas Forensic Science Commission conducted an exhaustive 6-month investigation into the scientific basis of bite mark evidence, ultimately recommending a moratorium on further use of this technique in Texas courtrooms. Because any conviction resting on bite mark evidence is inherently unreliable, the Texas Forensic Science Commission is currently conducting an audit into all Texas convictions resulting from bite mark evidence.
In addition to the 2009 NAS report, scientific findings such as the Texas Forensic Science Commission’s report and the President’s Council of Advisors on Science and Technology’s report on forensics in 2016 have affirmed that forensic bite-mark evidence is scientifically unacceptable and unlikely to ever be validated. The 2016 presidential report was unequivocal in its conclusion that “that bite mark analysis does not meet the scientific standards for foundational validity, and is far from meeting such standards. To the contrary, available scientific evidence strongly suggests that examiners cannot consistently agree on whether an injury is a human bite mark and cannot identify the source of [a] bite mark with reasonable accuracy.”
To date, at least 30 wrongful arrests or convictions have been linked to bite mark analysis and additional cases are still pending in courts around the United States, including capital cases. It is the Innocence Project’s hope that the landmark decision in Chaney’s case sets a new precedent against the use of unscientific evidence in courtrooms across the nation.
The Innocence Project, which is affiliated with the Cardozo School of Law, has worked for Steven Mark Chaney’s exoneration for many years and previously urged the Texas Forensic Science Commission to investigate the use of bite mark analysis in Chaney’s conviction. In addition to the Innocence Project, Chaney is represented by Julie Lesser, exoneration attorney of the Dallas Public Defender’s Office and the Southern Methodist University Innocence Clinic. The Innocence Project commends the work and support of Patricia Cummings, Cynthia Garza and the Texas Public Defenders Office and Judge Susan Hawk, a former Dallas district attorney, who joined the Innocence Project in seeking Chaney’s release and relief.
Steven Mark Chaney in his east Dallas home in December 2018. Photo: Ron Jenkins.