Demonstration for Troy Davis (Mehdi Fedouach/AFP/Getty Images)

Columbia law professor Patricia J. Williams blogs at the Nation about America's devotion to eyewitness testimony, despite a century's worth of studies revealing that, from Sacco and Vanzetti to Troy Davis, witnesses often get it wrong.

We see what we want to see,” my grandmother used to say. This insight visited me recently after I ran across the mall chasing a woman I thought was my cousin. It wasn’t, as it turned out, but I didn’t realize that until after I had puffed up behind her, bopped her amiably on the shoulder and cried out, “Boo!”

How was it possible, I thought in retrospective embarrassment, to so wrongly misidentify someone I know so well? Empirically my experience was all too common. I’d been thinking about my cousin a few moments before and saw the woman through the lens of those thoughts. We often project our life’s associations onto the faces of strangers. Constantly — if mostly unconsciously — we familiarize them with learned stereotypes. If we are wise, we learn to take caution with our assumptions. We recognize this innate fallibility, and most of the time it doesn’t matter very much.

Oddly enough, however, we reverse that supposition in the one context where fallibility matters most: in criminal cases, eyewitness testimony is viewed as the ne plus ultra for the prosecution, despite a century’s worth of psychological and sociological studies revealing that, from Sacco and Vanzetti to Troy Davis, witnesses misperceive a startling percentage of the time. “Human beings are not very good at identifying people they saw only once for a relatively short period of time,” writes Cornell law professor Michael Dorf. “The studies reveal error rates of as high as fifty percent — a frightening statistic given that many convictions may be based largely or solely on such testimony. These studies show further that the ability to identify a stranger is diminished by stress (and what crime situation is not intensely stressful?), that cross-racial identifications are especially unreliable, and that contrary to what one might think, those witnesses who claim to be ‘certain’ of their identifications are no better at it than everyone else, just more confident.” 

Read Patricia J. Williams' entire blog entry at the Nation.