Reasons not to trust police witnesses (that aren’t because they’re bastards)

It is a feature of the legal system that an arresting officer will often end up testifying in the court case. It is also a feature in our legal system that the police don’t always tell, as they are supposed to, the truth, the whole truth and nothing but the truth. I have seen court cases wherein police evidence has suggested the defendant has somehow managed to magically be in two places at once, charging a police line from both ends while simultaneously fabricating a complicated full face and head garment. I have seen court cases where video evidence has revealed that rather than assaulting a police officer, the defendant was assaulted by police officers.

The usual explanation put forward for these “minor inconsistencies” is that the police are a bunch of corrupt, vile pigs. While this may be true, science suggests that they can’t help but misremember.

In a study entitled Witnesses in action: the effect of physical exertion on recall and recognition [paywalled, alas], police officers were tested for their ability to recall details following physical exertion, similar to the sort of activity that a copper might encounter while arresting someone. In short, their ability to remember what happened or recognise a suspect was sorely diminished.

The participants were 52 experienced police officers, mostly male (which reflects the make up of the police force). Half of the participants were asked to beat up a big heavy bag of water–a slightly unnatural task, but presumably the university ethics panel refused to allow the researchers to use students as beating material. After this task, all of the participants went to raid the trailer of an imaginary “known criminal”, where they encountered a living room full of weapons, and an angry stooge yelling at them.

The police officers who had beaten up water recalled significantly–hugely–less about the stooge than those who had not exerted themselves. The exerted participants often could not identify their suspect from a line up.

Now, while this task is somewhat unnatural, it certainly casts damning doubt on the credibility of police evidence: arrests tend to happen after the arresting officer has been physically exerted in some way, and often in a rather aggressive fashion. Why, then, would the police lie in court rather than say “I don’t remember”?

Again, they might just be a bunch of filthy, corrupt pigs, but there may be a more benign reason for police officers saying something that is diametrically opposed to the realms of plausibility. A classic psychology study from the seventies can shed light on this. Loftus and Palmer studied the effects of leading questions, and found that it was very easy to manipulate participants’ memories of a situation by simple phrasing of questions. On watching videos of traffic accidents, participants could be lead to estimate a far greater speed for the accidents if the question involved the word “smashed” rather than “contacted”, and recalled seeing broken glass where there was none depending on the wording of another question.

If police officers have a fuzzy enough memory of a situation, a lawyer asking just the right questions can persuade their minds to fill in the blanks and begin remembering things that did not happen.

The author of the exertion study summarises her research by saying:

“The legal system puts a great deal of emphasis on witness accounts, particularly those of professional witnesses like police officers.  Investigators and courts need to understand that an officer who cannot provide details about an encounter where physical exertion has played a role is not necessarily being deceptive or uncooperative.  An officer’s memory errors or omissions after an intense physical struggle should not unjustly affect his or her credibility.”

I disagree. This absolutely should affect their credibility. We need not necessarily feel angry at the police, but every judge, magistrate and potential juror in the country ought to know that the police account–with its added weight of credibility as it comes from a person with higher social status–is likely to be flawed and possibly outright untrue.

As for those who have found themselves on the wrong end of police untruths in court, is it still worth suing the officers when it may not be their fault? Absolutely. This sends a clear message that if the officer does not remember something they should say so in court. They should be aware of the shortcomings of their own memory, rather than this being used as a tool for implicating people in crime.

The system has capitalised upon these quirks and inconsistencies in human memory for too long. This needs to end.


2 thoughts on “Reasons not to trust police witnesses (that aren’t because they’re bastards)”

  1. Good post, which manages to leave aside the suggestion that police systematically collaborate when writing up their statements. A suggestion which would be libellous, and absurdly hard to evidence, and which I would never make, of course, even if I personally knew it to be true.

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