Can anonymous evidence be used as evidence in a trial?

One fine day all the usual Internet places explode with a combination of still pictures, text, and video that do a pretty damned credible job of implicating Chicago police in a corruption and brutality scandal. Attempts to trace the origin of the information hit brick walls in the form of the fact torrent software doesn’t keep records, anonymous FTP site logs can be purged, and between Tor, Freenet, and I2P, it’s cryptographically hard to snoop on everything that goes down the series of tubes.

There’s no evidence any of it is forged. The police simply stonewall while the comment threads continue to smolder. Then the various Offices and Departments remember it’s an election year and, after all, there are names in the text and identifiable faces in the video and stills.

So, is any of the anonymously-supplied evidence going to be useful at trial? There’s nobody to cross-examine, nobody to testify as to how they came to make the files, and certainly nobody to intimidate out of testifying.

So – no.

No, none of this can be used in a criminal trial. There has to be a chain of custody to establish from where the evidence came originally.

I don’t know if this is applicable - probably not - but in some situations the court can take “judicial notice” of certain facts not in evidence, but this is usually limited to things that are patently obvious. Not sure if you could ever use this to circumvent chain of custody. But if there is a way to absolutely guarantee the authenticity of something like a video, it seems that it ought to be admissible.

As you say, judicial notice is taken only of things that are commonly accepted or beyond contradiction, i.e., “The court will take judicial notice that February 22, 2010 fell on a Monday” or “The court will take judicial notice that Jane Smith was chief of the Cecil City Police Department on the day in question.” (The parties can also stipulate to facts that like that). Judicial notice is not taken of matters that are in controversy, i.e. the authenticity of anonymous evidence that is at the heart of the prosecution’s case. You can bet that the accused police officers’ lawyers won’t stipulate to its authenticity or reliability. That said, it might still be used for administrative discipline, even if found inadmissible in a criminal prosecution.

I always assumed the purpose of anonymous information is to give the investigators some preliminary evidence so they can go out and find admissible evidence, whether just verifying the evidence given, or it leading to new evidence.

OK, I suspected as much. I thought there might be a special rule in place, though.

But that brings up another point: If the case goes to trial with other evidence, will the jury selection have to weed out anyone who might have seen the inadmissible stuff somewhere? In my hypothetical, the material becomes extremely widespread online and Chicago is hardly bereft of fast Internet access.

Depends on the evidence, and the bias.

Evidence that is impossible or hard to fake, like video footage is more likely to be admitted whereas evidence that is easy to fake, or impossible to link to the case definitively, are more likely to be excluded.

Also, evidence that is against a plaintiff is more likely to be excluded than evidence that is for a plaintiff.

Really? How would you lay a foundation for evidence whose origin is unknown, as the OP specifies? Who would you call as a witness and how would you establish that the item is genuinely what it purports to be?