How can you indict somebody for a crime that they didn't commit? But they might do. I find that a baffling concept. How is it justified?

2 Answers 2


What is the legal status of predictive policing?

You mean this?

First, "predictive policing" is a very wide concept. When police send officers to a sporting event or a protest rally they are practicing "predictive policing". If we are specifically considering the use of algorithms in making the predictions then that is perfectly legal although there is a moral hazard in perpetuating unfair biases.

How can you indict somebody for a crime that they didn't commit?

Theoretically, you can't - indictments have to follow the offence and they are leveled at the alleged perpetrator of that offence.

Practically, it happens all the time - innocent people get indicted for crimes due to all sorts of innocent mistakes, inadvertent biases and sometimes outright maliciousness.

I don't see what this has to do with "predictive policing" however.

  • "although there is a moral hazard in perpetuating unfair biases": presumably perpetuating unfair biases could also be illegal, depending on the bias and the circumstances surrounding its perpetuation. But that doesn't mean that predictive policing itself is illegal, of course. (Any police power or technique has the potential for misuse, yet police continue to be authorized to wield these powers and employ these techniques.)
    – phoog
    Nov 15, 2018 at 16:06
  • The use of algorithms in predictions isn't magically legal. It depends on what the algorithm does and how it's used. If a series of predictions are biased by some sort of protected class, it won't matter whether it's from the police chief or an algorithm. Something like predictive policing can lead to court cases, as in en.wikipedia.org/wiki/Stop-and-frisk_in_New_York_City. Nov 16, 2018 at 19:06
  • @DavidThornley an algorithm is a tool. There is nothing prohibiting the use of algorithms or of tools in policing, so both are legal. If a particular algorithm or tool has an illegal effect, however, then that use of that particular algorithm or tool is illegal, but even still the particular algorithm or tool itself is not necessarily illegal (think pistols).
    – phoog
    Nov 16, 2018 at 22:19
  • @phoog Right. If the algorithm produces legal effects, it's legal. If it produces illegal effects, people following it are at fault. I've just seen too many cases where someone does something stupid and/or harmful and excused themselves because they had an algorithm. Nov 19, 2018 at 4:55
  • @DavidThornley if an algorithm leads to something illegal, the people implementing it might also be at fault in addition to those following it. But I suppose the key point here is that while it is literally true that "using algorithms in policing is legal" in the general case, many people, especially those who haven't spent much time considering the issues, might misunderstand the statement as applying to all cases, where it is clearly not true.
    – phoog
    Nov 19, 2018 at 14:07

The determination of whether a person did a thing is made at trial, so actual guilt logically has to be follow the accusation. Whether or not that formal accusation is in the form of a grand jury indictment (as must be the case in US federal crimes, pursuant to the 5th Amendment), or by a prosecutor filing a charging document with the court, this has to be done before the accused is legally proven to have committed the act. There is a legal rule to the effect that if there is not probable cause to say that that the accused committed the alleged act, the charge must be dismissed. So not only do you have to have good-enough reason to think that the accused did the act, you also have to have good enough reason to think that the act too place.

A runaway grand jury could indict a person on the belief that he may commit a criminal act, but such an indictment would be dismissed in court because no actual crime had occurred.

  • -1: What's a runaway grand jury and why do you consider that at all relevant to what I'm asking? Nov 14, 2018 at 19:51
  • A grand jury can return an indictment, regardless of what the law says: a grand jury can do anything it wants, and when they go out of control, that is known as a "runaway grand jury". Therefore it is possible for there to be an indictment based on a legally irrelevant belief about a future crime. Indictment is not the relevant legal distinction to make, instead, 'viable prosecution' would be. Such an indictment would simply be dismissed by the court.
    – user6726
    Nov 14, 2018 at 20:16
  • @MoziburUllah your question seems (to me at least) to be suggesting that predictive policing could be used to indict or charge someone for a crime that was not committed (although I don't see any evidence that this actually happens), and this answer seems to be addressing that. If that idea is actually not relevant to your question, then perhaps you could clarify the question. As noted in the other answer, it is not clear what "indicting somebody for a crime that they didn't commit" has to do with "predictive policing."
    – phoog
    Nov 15, 2018 at 16:11
  • @user6726: I can't say I have heard the term before which I was asking. For some reason my mind jumped to 'runaway slave.' Dunno why. Nov 16, 2018 at 17:07
  • @phoog: To predict is to suspect - no? Nov 16, 2018 at 17:08

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