Forensic Science: Trials with Errors

What appears to be accepted science in the courtroom may not be accepted science among scientists.

Getty Images

Illustration of a Bohr atom model spinning around the words Science Quickly with various science and medicine related icons around the text

Join Our Community of Science Lovers!

We have increasing doubts about this evidence, but we don’t feel yet that we have the scientific knowledge and basis to exclude it altogether.”

Jed Rakoff, United States District Judge for the Southern District of New York. He spoke about forensic evidence—and the need for it to actually be based in science—at the annual meeting of the American Association for the Advancement of Science in Boston on February 18th.

In 2009 the National Academy of Sciences issued a report critical of a lot of the forensic evidence in the courtroom.


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


“Most fundamentally…the report said that what was really lacking was testing and research. And thus they questioned whether any of this could be called science and they also questioned whether it was really that accurate…

But forensic evidence is still widely admitted, even when the science behind it may be lacking.

I think courts continue, despite their doubts, to admit this evidence…and that is still the feeling…that, eh, it’s still better than nothing, it’s still useful evidence, it has some degree of objectivity that’s not present in much lay testimony. And therefore it is useful. The problem of course is it comes heralded as science, and that gives it a weight that is probably disproportionate.

I had a case, this was before the National Academy report, but it’s sort of illustrative of what I’m talking about…United States versus Glynn. In that case, the government put on a tool-mark expert to testify that the markings on the shell that had been found at the scene of the crime matched the markings inside the barrel of the gun that had been found under the defendant’s bed…and I asked him, for example, what’s your error rate and what’s the error rate of this methodology that you’re using. And he said zero. And I said zero? And he said yes. And I said how can it be zero. And he said well, in every case I’ve testified, the guy’s been convicted.”

—Steve Mirsky

[The above text is a transcript of this podcast.]

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American

Subscribe