Posted by: bridget | 3 May 2007

DNA, Wrongful Convictions, and Line-Ups

Recently, the Innocence Project exonerated its 200th person through DNA evidence.  Its analysis of the wrongfully convicted indicates that 60% of them are black or Latino and 85% of them are black men accused of assaulting white women, although black men are only accused of 1/3 of the assaults on white women.  (Of course, the statistics are somewhat imperfect because it is unclear of whether or not the Innocence Project has performed DNA tests without regard for race or gender.  Likewise, wealthier white men may have access to DNA testing and the money to afford it, while Latinos and blacks, who tend to be poorer, would need private aid.)  

As the Washington Post reports, the work of the Innocence Project has resulted in changes in the criminal justice system.  One of the main problems with criminal convictions is eyewitnesses.  It is among the least reliable ways of determining whether the defendant was the person who committed the crime, but juries give the most weight to eyewitness identifications.  Most line-ups are not double-blind (the standard for scientific rigour): the policeman who escorts the victim or the eyewitness is aware of who the suspect is and will, deliberately or subliminally, encourage the witness to pick the suspect. 

Witnesses are sometimes shown photo arrays of suspects and are later taken through a line-up.  If the photo array contains the same individuals as the line-up, that individual will look familiar to the witness, because she saw his picture shortly before the line-up, not because he is the perpetrator.  Furthermore, eyewitnesses are more accurate when they see a sequential line-up (i.e. the witness sees each person in the line-up one at a time, instead of in a row). 


  1. “Its analysis of the wrongfully convicted indicates that 60% of them are black or Latino and 85% of them are black men accused of assaulting white women, although black men are only accused of 1/3 of the assaults on white women.”

    These kind of statistics always require A LOT of examination. A few possible problems with this stat would include:

    1. Although most crime is intra-racial, inter-racial crime is overwhelmingly black on white. Why would the haves commit crimes against the have-nots? I believe the numbers are close to 75% to 25%. So it is not surprising to see the same kind of thing in these statistics.

    2. Inter-racial cases also come with more suspected bias. We come to view the case as a society wary of racism, so we often expect racism in places where it doesn’t exist. I wouldn’t be suprised if the Innocence Project found many of these cases interesting for that very reason.

    3. Well I have to get to work, so two responses will have to be good enough for now.

    I will leave you with one question. If the fact that the prison population is something like 45% black means that the justice system is racist, does the fact that the prison population is 94% male mean it is even more so sexist?

  2. Interesting. TT’s comment interesting as well. Either way it makes me happy that innocents are being exhonerated.

    I agree with you on the double blind line up (how it should be). It seems that was not done in the duke case that was all over the headlines. If that is the way it is normally dont that is a tragedy. With Virginia Tech it also looks like the police quickly arrived on a theory that it was the boyfriend of the first girl.

  3. Agreed, TT and Zabs.

    I tried to point that out with my parenthetical – that those exonerated are not necessarily the same as those who are incarcerated. If the Innocence Project does DNA sampling for 150 black men and 15 white men, with the result that 85 black men and 15 white men get off, it’s not that the criminal justice system is racist.

    As for your remark, TT, it depends on whom you ask. GreetingsMySon (and his ilk) do think that the system is prejudiced against men because they are most often the victims of violent crimes and more men are incarcerated. (Of course, it slips people’s minds that if more MEN commit crimes, and they commit them against men, then it’s just and fair that more men ought to be victims and more men ought to be incarcerated.) Woman-on-man and woman-on-woman violent crime is extremely rare.

  4. “His ilk”. I admire your restraint.

    Although I am very much a law and order type guy, (did you just hear that music?) I also am aware that there is often pressue to “solve” the case rather than get the right perp. Big problem given the resources available to the government as compared to those “typically” available to John Q. Citizen. 95% of America is in the slammer in the Duke case, but they had resources to mount a defense.

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