The reliability of bloodstain-pattern analysis has never been definitively proven or quantified, but largely due to the testimony of criminalist Herbert MacDonell, it was steadily admitted in court after court around the country in the 1970s and ’80s. MacDonell spent his career teaching weeklong “institutes” in bloodstain-pattern analysis at police departments around the country, training hundreds of officers who, in turn, trained hundreds more.
While there is no index that lists cases in which bloodstain-pattern analysis played a role, state appellate court rulings show that the technique has played a factor in felony cases across the country. Additionally, it has helped send innocent people to prison. From Oregon to Texas to New York, convictions that hinged on the testimony of a bloodstain-pattern analyst have been overturned and the defendants acquitted or the charges dropped.
In 2009, a watershed report commissioned by the National Academy of Sciences cast doubt on the discipline, finding that “the uncertainties associated with bloodstain-pattern analysis are enormous,” and that experts’ opinions were generally “more subjective than scientific.” More than a decade later, few peer-reviewed studies exist, and research that might determine the accuracy of analysts’ findings is close to nonexistent.
Blood spatter analysis isn’t quite as nonsense as the rest.
If blood is found underneath an object, you know that the blood got there first, and the object second. If you find a drop of blood among a bunch of fine mist, you may be able to predict that the fine mist is blood from a victim after a gunshot, while the drop might be from someone else, possibly the perpetrator.
Of course there are other observations which are misinterpreted, but the fact remains that blood spatter follows the laws of physics; therefore, it is possible to discover factual information from observing it.
Sure, but that’s not what police refer to when they talk about blood spatter analysis. I’m not saying it’s impossible to get good evidence from the location of blood; I’m saying that the bullshit they do around drop size and splatter patterns does not have any evidence to support it.
Edit: in other words, they want the credibility of science without doing the hard work of peer-review or falsification.
From ProPublica:
If blood is found underneath an object, you know that the blood got there first, and the object second. If you find a drop of blood among a bunch of fine mist, you may be able to predict that the fine mist is blood from a victim after a gunshot, while the drop might be from someone else, possibly the perpetrator.
Of course there are other observations which are misinterpreted, but the fact remains that blood spatter follows the laws of physics; therefore, it is possible to discover factual information from observing it.
Sure, but that’s not what police refer to when they talk about blood spatter analysis. I’m not saying it’s impossible to get good evidence from the location of blood; I’m saying that the bullshit they do around drop size and splatter patterns does not have any evidence to support it.
Edit: in other words, they want the credibility of science without doing the hard work of peer-review or falsification.