Now, their skepticism is about informants, generally, and doesn’t have anything to do with Cohen or the Mueller investigation specifically. Moreover, incentivized informant testimony — both from accomplice witnesses and from “jailhouse informants” who pass on information gleaned from cell mates — isn’t inherently bad, said Jeffrey Neuschatz, professor of psychology at the University of Alabama in Huntsville. Nobody knows the rates at which they provide inaccurate information (although we do know that humans are willing to alter their behavior in big ways for even small incentives). And both law enforcement and prosecutors say these kinds of witnesses are sometimes necessary to prove a case — especially ones involving complex criminal enterprises where it might be easy to catch a low-level perpetrator and much harder to catch his boss’ boss.

But what we do know is that, when researchers study situations where people went to prison for crimes they did not commit, informant testimony was one of the four major factors contributing to those convictions.