Is there a constitutional right not to be convicted based on junk science? For years, the U.S. Supreme Court has failed to directly grapple with that question — so much so that Justice Sonia Sotomayor recently said that Congress and state legislatures should tackle the problem now instead of waiting on the courts to fix it.

On July 2, the court unanimously declined to review the case of Charles McCrory, who was convicted in Alabama in 1985 for the murder of his wife, based almost exclusively on bogus bite-mark testimony. Bite-mark analysis has been roundly discredited by scientists and, to date, is behind at least 39 wrongful convictions or indictments.

Bite-mark evidence is among a host of problematic, scientifically questionable forensic practices widely used in the criminal legal system. While a number of forensic practitioners have acknowledged the problem and sought to get their disciplines on firmer scientific footing, the law has not caught up. Ostensibly, courts are supposed to vet forensic evidence before trial, though because judges are not scientists — and most lack any science training — this is rarely effective, and they often allow even the most questionable science into evidence.

For people like McCrory subsequently convicted based on junk science, there is often no straightforward way for the courts to revisit or correct old cases based on outdated and debunked forensic practices. The law favors finality, so once someone is sent to prison, it becomes difficult to challenge a conviction based on junk science, and judges often deny appeals based on procedural matters without ever engaging with those flaws.

While the Supreme Court has occasionally acknowledged this problem, among her colleagues, Sotomayor was alone in calling out the crisis it has created. In a statement alongside the denial of McCrory’s appeal, Sotomayor described his case as a symptom of a broader problem.

“Hundreds if not thousands of innocent people may currently be incarcerated despite a modern consensus that the central piece of evidence at their trials lacked any scientific basis.”

“This petition raises difficult questions about the adequacy of current postconviction remedies to correct a conviction secured by what we now know was faulty science,” Sotomayor wrote. “Hundreds if not thousands of innocent people may currently be incarcerated despite a modern consensus that the central piece of evidence at their trials lacked any scientific basis.”

To date, a handful of states have created a direct avenue of appeal for defendants convicted based on junk or debunked science. Texas was first, and Sotomayor notes that the statute has been used to exonerate a man named Steven Mark Chaney, who was convicted on bogus bite-mark evidence. California has a similar statute, which was used to exonerate Bill Richards, also convicted on discredited bite-mark analysis.

“These statutes,” Sotomayor wrote, “create an efficient avenue for innocent people convicted based on forensic science that the scientific community has now largely repudiated.”

A Flimsy Piece of Evidence

Throughout the nearly four decades since his wife’s murder, McCrory has maintained his innocence. In 2022, The Intercept published a lengthy investigation into........

© The Intercept