Bite mark evidence is still admissible in court in some jurisdictions, but its standing has collapsed over the past fifteen years and courts are increasingly refusing to let juries hear it. There is no nationwide ban. What has changed is that three federal scientific reviews have concluded the technique lacks a valid foundation, and defense attorneys now have the material to win exclusion arguments that would have failed a generation ago.
When bite mark testimony does reach a jury today, judges typically restrict what the examiner can say. The sweeping “match to the exclusion of all others” testimony that produced wrongful convictions in the 1980s and 1990s is largely gone.
Why Admissibility Has Shifted
Three federal scientific reviews — in 2009, 2016, and 2023 — have each concluded that bite mark analysis does not rest on sound science. Those reports are what defense attorneys now put in front of judges during admissibility hearings.
The National Academy of Sciences reported in 2009 that “the uniqueness of the human dentition has not been scientifically established,” that skin had not been shown to reliably record whatever pattern teeth produce, and that controlled studies showed “widely differing results and a high percentage of false positive matches” among examiners.
The President’s Council of Advisors on Science and Technology went further in 2016, concluding that “bitemark analysis does not meet the scientific standards for foundational validity, and is far from meeting such standards.” PCAST found examiners could not consistently agree even on whether an injury was a human bite mark. The report recommended that the Department of Justice stop presenting bite mark evidence in court.1The White House. Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods
The National Institute of Standards and Technology issued the most comprehensive assessment in 2023. NIST concluded that “forensic bitemark analysis lacks a sufficient scientific foundation” because all three core premises of the field had failed: dental patterns have not been shown to be unique, those patterns do not transfer accurately to skin, and examiners cannot reliably analyze the marks to include or exclude suspects.2National Institute of Standards and Technology. Bitemark Analysis: A NIST Scientific Foundation Review
The practical problems the reviews identified are consistent. Skin stretches, swells, bruises, and heals, distorting whatever pattern was left behind. A 2010 study cited in the PCAST report found that “skin deformation distorts bitemarks so substantially and so variably” that comparison was essentially meaningless. Examiners looking at the same injury frequently disagree about what they see and whether a suspect should be included or excluded.
The Legal Standard a Judge Applies
Whether bite mark testimony reaches a jury depends on the evidentiary standard in the jurisdiction. Two frameworks dominate.
Daubert
All federal courts and a majority of states apply the standard from Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993). The trial judge serves as a gatekeeper, evaluating whether expert testimony rests on a reliable scientific foundation. The Supreme Court identified factors to consider: whether the method can be tested, whether it has been subjected to peer review, its known or potential error rate, and whether it has attracted widespread acceptance in the relevant scientific community.3Justia. Daubert v. Merrell Dow Pharmaceuticals, Inc.
Bite mark analysis struggles on every factor. It has no established error rate. Validation studies have produced discouraging results. Acceptance within the forensic odontology community itself is fracturing.
Frye
A minority of states still apply the older standard from Frye v. United States (1923). Under Frye, scientific evidence is admissible only if the method behind it has gained “general acceptance” within the relevant scientific community.4Legal Information Institute. Frye Standard The growing number of forensic odontologists who have publicly disavowed bite mark analysis makes “general acceptance” an increasingly difficult claim for prosecutors to sustain.
Federal Rule of Evidence 702
Daubert is codified in Federal Rule of Evidence 702, which was amended in December 2023. The rule now explicitly requires the party offering expert testimony to demonstrate that “it is more likely than not” that the expert’s opinion reflects reliable principles, methods, and application. The amendment raised the bar in federal court and gives judges clearer authority to exclude techniques that lack a solid foundation.5United States Courts. Federal Rules of Evidence
What Courts Are Actually Doing
For decades, courts admitted bite mark evidence routinely, often because other courts had admitted it before. The NAS, PCAST, and NIST reports gave defense attorneys concrete, authoritative material to break that cycle.
Under Daubert, a defense attorney challenging bite mark evidence points to the absence of validated error rates, the failure of peer-reviewed studies to support the method, and the PCAST and NIST conclusions that the technique lacks foundational validity. Under Frye, the defense argues that forensic odontologists renouncing the practice undermines any claim of general acceptance. Both arguments are substantially easier to win than they were a decade ago.
The National Institute of Justice maintains a database tracking court decisions on forensic evidence admissibility issued after the 2016 PCAST report.6National Institute of Justice. Post-PCAST Court Decisions Assessing the Admissibility of Forensic Science Evidence At least one state forensic science commission has recommended a moratorium on bite mark evidence until further research validates the method. That recommendation is not binding on judges, but it signals where the field is heading.
Prosecutors have taken notice. Introducing bite mark evidence now almost guarantees a lengthy admissibility hearing, and losing it on the record can damage credibility on other evidence. Many prosecutors simply avoid relying on it.
What Admitted Testimony Looks Like Now
In the increasingly rare cases where a court allows bite mark testimony, its role is sharply limited compared to what juries heard in the 1980s and 1990s. An expert today would likely be permitted to testify only that a suspect’s dental pattern is “not inconsistent with” an injury. Definitive identification testimony — the “this defendant and no one else” claim that drove wrongful convictions — is generally prohibited.
Even with those restrictions, admitted bite mark evidence becomes a target on cross-examination. A defense attorney armed with the NAS, PCAST, and NIST reports can walk the jury through the technique’s scientific failures: no proof that teeth are unique, no reliable transfer of patterns to skin, and high disagreement rates among examiners looking at the same mark. Jurors who hear that cross-examination are unlikely to treat the testimony as anything close to conclusive.
The Wrongful Conviction Record Behind the Shift
The urgency driving exclusion arguments is not abstract. As of 2021, at least 29 people in the United States had been exonerated after being convicted in cases where bite mark evidence was used in the original prosecution, along with 7 additional wrongful indictments. Those wrongful convictions totaled approximately 424 years of imprisonment.
Keith Allen Harward is the most-cited example. Six forensic odontologists testified at his prosecution that his teeth matched marks on the victim of a sexual assault. He served more than 33 years of a life sentence, narrowly escaping the death penalty, before DNA evidence proved his innocence and identified the actual perpetrator.
Across the documented exonerations, the pattern repeats: confident expert testimony that a suspect’s teeth were a match, combined with minimal other physical evidence. DNA testing — the one forensic method all three federal reviews found scientifically valid — proved the convictions wrong.
Challenging an Older Conviction
For someone already convicted on bite mark evidence, the path back into court depends on the mechanisms available in their jurisdiction. A growing number of states have enacted laws that specifically allow convicted individuals to seek relief when the forensic science used against them has been discredited or fundamentally undermined since trial. These statutes generally require the convicted person to show that new scientific evidence was unavailable at the time of trial and that, had it been presented, there is a reasonable likelihood the outcome would have been different.
Eligible individuals typically include people currently incarcerated, on parole or probation, subject to sex offender registration, or in some states those who have completed their sentences. Some states allow claims regardless of whether the original conviction followed a trial, a guilty plea, or a no-contest plea. The argument in a bite mark case is straightforward: three federal reviews have concluded the technique lacks validity, and no competent forensic odontologist could offer the same testimony today that was presented at the original trial.
In jurisdictions without a specific changed-science statute, traditional post-conviction remedies and habeas corpus petitions remain available, though the procedural hurdles are higher. An attorney experienced in post-conviction work can evaluate which path offers the best chance of relief based on the facts and jurisdiction involved.