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Science refutes bite mark evidence but courts lag behind

On Behalf of | Nov 15, 2022 | Uncategorized

The validity of bitemark evidence has continued to face intense scrutiny and criticism in California, but the criminal legal system still hasn’t been able to face the facts. Over two dozen of the people who have faced arrests or convictions because of evidence from bitemarks were later exonerated of the crime. For the legal system to catch up, it would mean acknowledging the mistakes that have been made for years because of unfounded trust in this discipline.

What makes bitemark evidence so unreliable?

The problem with using bitemark evidence is that it’s a very inexact science. There’s plenty of room for error when attempting to match a person’s teeth with the impressions left on another person’s skin even to the most trained eye. This makes it highly problematic when it comes up in criminal defense cases.

The skin doesn’t work as a perfect mold, so the impression will never be perfectly preserved. And then there’s the question of which angle the bite came from and whether there were multiple bites involved. Because of these and myriad other variables, there almost always must be some guesswork involved in gathering this type of evidence.

Groups like the National Institute of Standards and Technology as well as the National Academy of Sciences have pointed out the issue of bitemark evidence‘s lack of foundations in science. Their research continues to reveal the dangers of bitemark evidence being permissible in court, showing how unreliable it is. This conclusion has only become more clear with each study.

The three assumptions of bitemark evidence

In order for the science behind bitemark evidence to work, there are three assumptions that have to be true. One is the idea that everyone has a unique dental alignment, and thus their bite would be like a fingerprint.

Next is the belief that human skin makes a significant, detailed and lasting enough impression to show a person’s unique bite. And lastly, you have to assume that an expert would be able to analyze those bites and match them to the right person’s teeth. Each of these assumptions has been shown by recent studies to be dubious at best.