Snitching

Criminal Informant Law, Policy, and Research

Forensics

U.S. Supreme Court decides case on expert admissibility

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The Supreme Court decided a case on Thursday that is not about informants but that could have implications down the road for informant expert testimony. In Diaz v. United States (June 20, 2024), the Court held that a federal agent could testify as an expert that “most drug couriers” know they are transporting drugs. The defendant, Delilah Guadalupe Diaz, claimed that she did not know that drugs were in the car that she was driving. The Court reasoned that the agent was not testifying explicitly about what Diaz knew or did not know — that would have been prohibited by the Federal Rules of Evidence, Rule 704(b)— but only what “most people” in that group know. The majority rejected the dissent’s argument that the expert “functionally” stated an opinion about Diaz’s state of mind, because “[t]hat argument mistakenly con­flates an opinion about most couriers with one about all cou­riers.”  Rather, the Court held that “an expert’s conclusion that most people in a group have a particular mental state” is not an opinion about a particular individual in that group.

Diaz potentially enhances the admissibility of defense expertise regarding informants, specifically about whether informants know that they will receive benefits in exchange for the information they provide. As I and many other scholars have pointed out, most informants know that they will be rewarded for incriminating other people, even if the government has not expressly or formally promised them anything up front.  Nevertheless, the government often maintains that informants come forward for no reward, and informants will often tell the jury that they do not expect any reward.  In a similar vein, prosecutors often reassure juries that informants are reliable because lying informants will fear prosecution for perjury, but most informants (as well as lawyers and judges) know that such prosecutions are extremely rare. Expert testimony on what “most informants know” could thus be helpful to juries in deciding whether informants should be believed.

Courts are typically more willing to allow government experts than defense experts in criminal cases.  Indeed, the National Academies of Sciences issued a report in 2009 worrying that “trial judges rarely exclude or restrict expert testimony offered by prosecutors.” But Diaz cuts both ways. In her concurrence, Justice Ketanji Brown Jackson emphasizes that the decision is “party agnostic” and that “[b]oth the Government and the defense are permitted [] to elicit expert testimony ‘on the likelihood’ that a defendant had a particular mental state.”

Here is a link to an explainer about informant expert testimony that I wrote for The Appeal.  And here is a link to my colleague Professor Noah Feldman’s op-ed arguing more generally that Diaz was wrongly decided, and that it impermissibly waters down the prosecution’s obligation to prove its case beyond a reasonable doubt “because [the decision] invites the jury to conflate abstract statistical probabilities with the specific circumstances of the individual case.”

Hawaii wrongful conviction used snitches to bolster weak DNA evidence

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Albert “Ian” Schweitzer spent 25 years in prison for a murder he did not commit, based on faulty DNA testing and two different lying informants–one drug defendant and one jailhouse informant. The first informant received probation instead of significant jailtime and avoided federal prosecution. The jailhouse snitch avoided retrial and a potential 10-year sentence. Story from the Hawaii Innocence Project here: Ian Schweitzer Exonerated of Murder After 25 Years in Hawaii. Thanks to Radley Balko’s The Watch for highlighting the story.

The case is an example of a larger forensic problem. Jailhouse snitch testimony often comes into existence in order to bolster weak cases. High profile murders tend to generate snitch testimony since informants know that rewards are forthcoming. The problem is worse for weak cases: if the case were strong, the government wouldn’t need the snitch. The confluence creates a pernicious storm of inaccuracy where bad evidence makes other bad evidence look better than it actually is. For more examples see this previous post about dog sniff and arson bolstering.

Connecticut Supreme Court issues decision on informant experts

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The Connecticut Supreme Court has decided that informant experts like myself are admissible when they can provide specialized information to jurors about informant unreliability, namely, information that jurors would not otherwise know based on common sense or from the popular culture or general media.  The Supreme Court upheld the exclusion of my testimony in this particular case, but noted that such testimony is not per se inadmissible, and it imagined other scenarios in which expert testimony might be admitted. The 2019 case, State v. Leniart, overturned this 2016 decision, in which the Connecticut Court of Appeals held that the trial judge made a mistake in preventing me from testifying before the jury.

I explain what the Leniart decision means in more detail in this piece for The Appeal: Why Juries Need Expert Help Assessing Jailhouse Informants.  In particular, I explain why jurors are unlikely to understand the full scope of informant practices, fabrications, and motivations to lie, and therefore would be helped by hearing expert testimony:

“Informants are highly motivated to give persuasive, believable testimony in exchange for their own freedom. They can also receive money, drugs, sex, food, and phone privileges when they cooperate with jail officials. Some scour the newspapers, pay other inmates for information, or get family members to pull court records so that they can come up with incriminating testimony against their cellmates. Some jurors may already know about these sorts of practices; many will not.”

The developing science of informant cognition

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Behavioral psychologists have been studying the informant phenomenon, especially the thorny question of why jurors believe unreliable informants even when they know that the informants have strong incentives to fabricate evidence.  Some of those studies can be found here in the Resources & Scholarship section.

A group of researchers recently published this study finding that information from an informant can affect other witnesses in a case. Specifically, the study found that eyewitnesses who identified suspects in a line-up actually changed their identifications after learning that a jailhouse informant had implicated a different suspect.  Here is the abstract:

“Prior research has shown that primary confession evidence can alter eyewitnesses’ identifications and self-reported confidence. The present study investigated whether secondary confession evidence from a jailhouse informant could have the same effect. Participants (N = 368) watched a video of an armed robbery and made an identification decision from a photo lineup. Except for those in the no-feedback conditions, all participants then read that certain lineup members either confessed to the crime, denied involvement, or were implicated by a jailhouse informant. Jailhouse informant testimony implicating the identified lineup member led participants to have significantly higher confidence in their identification. In contrast, jailhouse informant testimony that implicated a lineup member other than the identified led participants to have significantly lower confidence in their initial identification, and 80% of these witnesses changed their identification. These results indicate that jailhouse informant testimony can influence eyewitnesses’ confidence and their identification decisions.”

Preston M. Mote & Jeffrey S. Neuschatz & Brian H. Bornstein & Stacy A. Wetmore & Kylie N. Key, Secondary Confessions as Post-identification Feedback: How Jailhouse Informant Testimony Can Alter Eyewitnesses’ Identification Decisions, Journal of Police and Criminal Psychology (2018).

We already know that informant testimony can arise to bolster weak cases, providing corroboration for faulty forensic evidence or uncertain eyewitness identifications.  This new study suggests that in addition to bolstering, informant testimony can actually alter other witnesses’ testimony. 

Experiments on the impact of inducements

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Scholars at the University of Arizona Law School have published a paper entitled “Incentives, Lies and Disclosure,” 20 U. Pa. J. Con L. 33 (2018).  They conduct a number of behavioral experiments and conclude that incentivized witnesses like jailhouse informants are more likely to lie, and that even when potential jurors are told about the incentives, they still believe the witness.  Here is the abstract:  

Prosecutors can force witnesses to testify and use perjury prosecutions to hold them to the provable truth. More controversially, prosecutors also offer witnesses inducements for favorable testimony, including leniency, immunity, and even cash. This ubiquitous behavior would be illegal as witness bribery, except for a longstanding tradition of sovereigns using this power, which legal doctrine now reflects. A causal analysis shows that even if prosecutors use this power only in good faith, these inducements undermine the epistemic value of witness testimony. 

Due process requires, and legal doctrine assumes, that when such inducements are disclosed to the jury, they will discount the witness testimony accordingly. However, juries’ success in doing so is an empirical question. We conducted three randomized experiments with 1,000 human subjects in roles of witnesses and jurors deciding vignettes based on real cases. We find that incentives have large effects on witnesses, allowing prosecutors to routinely procure favorable testimony regardless of its truth. Yet, disclosure has no detectable effects on either witnesses or jurors. 

We discuss two potential reforms. First, courts could borrow from the practice with expert witnesses and use the current rules of evidence to conduct Daubert-like pretrial screening of incentivized witnesses for reliability. We frame the appropriate counterfactual question about whether the incentives would cause a witness to give the same testimony even if it were false. Second, we present the novel suggestion that prosecutors could decide whether to offer benefits to a witness based on whether she will testify to material information, but without knowing whether the information is favorable to the Government. These mechanisms may preserve the value of incentives to produce information, while minimizing false testimony.