Whether confidential informants have to testify in court depends almost entirely on what the informant did in the case. A CI who only passed along a tip that started an investigation rarely has to take the stand and usually stays anonymous. A CI who set up the deal, was present during the alleged crime, or was the other party in the transaction can be compelled to testify, and if the government refuses to produce them, the case often gets dismissed. The controlling framework comes from the Supreme Court’s 1957 decision in Roviaro v. United States, which requires courts to weigh the government’s interest in protecting its sources against the defendant’s right to a fair trial.
Why the Government Wants the Informant Kept Secret
Prosecutors start with a real legal advantage here. Courts recognize what’s known as the “informer’s privilege,” a right the government holds to keep a CI’s identity confidential. The reasoning is practical: people are more willing to report criminal activity when they know their names won’t be handed over to the person they’re informing on. Without that assurance, sources dry up.
The privilege belongs to the government, not the informant. A prosecutor invokes it, and only a court can override it. That override is exactly what a defendant has to secure to force a CI onto the stand.
Tipster or Active Participant
The single factor that decides most CI disclosure fights is the informant’s role in the alleged offense.
A tipster provides a lead and then disappears from the story. Someone tells police that drugs are being sold from a particular address; officers set up their own surveillance, get a warrant, and gather their own evidence. Nothing at trial actually depends on what the tipster saw or said. Courts routinely refuse to unmask this kind of informant because their testimony wouldn’t meaningfully help the defense.
An active participant is a different situation. This is a CI who arranged the meeting, was present during the transaction, wore a wire, or was the person the defendant supposedly sold to. Now the informant is a percipient witness to the crime itself. Questions like whether the defendant knew what was in the package, whether the informant pressured the defendant into the deal, or what was actually said during the meeting may have answers that live only with the CI. When that’s the case, the defense has a strong argument that the informant has to testify or the case can’t go forward.
The Roviaro Balancing Test
In Roviaro v. United States, the government refused to identify an informant who had been the sole participant alongside the defendant in a heroin transaction. The Supreme Court reversed the conviction and held that when disclosure of an informant’s identity “is relevant and helpful to the defense of an accused, or is essential to a fair trial, the Government’s privilege to withhold disclosure of the informer’s identity must give way.”1Justia U.S. Supreme Court Center. Roviaro v. United States
The Court deliberately declined to set a fixed rule. Instead it laid out a case-by-case balancing test that weighs the public interest in protecting the flow of information to law enforcement against the defendant’s right to prepare a defense. The relevant factors include the crime charged, the possible defenses, and the significance of the informant’s potential testimony.1Justia U.S. Supreme Court Center. Roviaro v. United States A defendant charged with selling drugs directly to a CI has a much stronger argument than one whose case simply began with an anonymous phone call.
The Sixth Amendment sits behind all of this. It guarantees the accused the right “to be confronted with the witnesses against him,”2Congress.gov. Amdt6.5.1 Early Confrontation Clause Cases and in Crawford v. Washington the Court held that testimonial out-of-court statements cannot be admitted at trial unless the person who made them is unavailable and the defendant previously had a chance to cross-examine them.3Justia U.S. Supreme Court Center. Crawford v. Washington If a prosecutor tries to slip an informant’s statements to police into evidence without putting the CI on the stand, the defense has a separate constitutional objection.
How the Defense Forces the Issue
Nothing happens automatically. The defense has to file a motion asking the court to order the prosecution to identify the informant. The motion can’t be speculative. The defense needs to show concretely that the CI’s testimony would be relevant and helpful to a specific defense theory, whether that’s entrapment, misidentification, lack of knowledge, or something else.
The judge typically resolves the dispute through an in camera hearing, held privately outside the presence of the defendant and defense counsel. The prosecutor presents evidence about the informant’s actual role, sometimes including the informant’s own testimony given under seal. A court reporter is present and the transcript stays sealed. The judge’s task is to decide whether keeping the identity secret would deprive the defendant of a fair trial.
If the judge concludes the CI was just a tipster, the motion is denied and the identity stays protected. If the judge finds the CI was a material witness, the motion is granted, and the prosecution then faces a choice: reveal the informant so the defense can subpoena and cross-examine them, or drop the charges.
What Happens If the Government Refuses
When a court orders disclosure and the prosecution won’t comply, courts have real tools. The judge can dismiss the charges, suppress the evidence that depended on the CI’s involvement, or strike officer testimony that relied on information from the undisclosed source. In Roviaro itself, the failure to require disclosure was treated as reversible error and the conviction was overturned.1Justia U.S. Supreme Court Center. Roviaro v. United States
This is why the decision to fight a disclosure order is really a calculation about whether protecting the source is worth losing the case. In many instances, the government simply drops the charges rather than expose the CI.
Deals and Incentives the Prosecution Must Disclose
Even when a CI’s identity is out in the open, the prosecution carries separate constitutional obligations. Under Brady v. Maryland, prosecutors must disclose evidence favorable to the defendant and material to the outcome.4Justia U.S. Supreme Court Center. Brady v. Maryland Under Giglio v. United States, that obligation reaches impeachment evidence, including anything that undermines a witness’s credibility.5Legal Information Institute. Giglio v. United States
CIs almost always receive something for their cooperation. Common incentives include reduced or dropped charges, immunity from prosecution, favorable sentencing recommendations, immigration benefits such as visa assistance, monetary payments, and relocation help.6U.S. Department of Justice. 9-5.000 Issues Related to Trials and Other Court Proceedings Every one of those arrangements has to be disclosed to the defense. If prosecutors hide a deal and the defendant is convicted, the conviction can be overturned when there’s a reasonable probability the outcome would have been different had the jury known.
Challenging a CI Who Does Testify
When a confidential informant takes the stand, the defense has wide latitude to attack their credibility. The Sixth Amendment guarantees not just the right to cross-examine but specifically the right to explore a witness’s bias, and trial judges have no discretion to block relevant cross-examination on that subject.
Cross-examination of a CI usually focuses on a handful of areas. What did the government promise, and what is the witness getting out of testifying? What does the informant’s own criminal history look like? How many times has this person worked as an informant before, and what did they receive in those cases? Did the informant tell the handler one version of events and then say something different on the stand? A pattern of trading testimony for leniency, combined with a specific deal in the current case, is powerful impeachment material. Juries tend to view informant testimony skeptically once they hear what the witness stands to gain, which is one reason prosecutors sometimes prefer to build cases around physical evidence and officer testimony and keep the CI off the stand entirely.
When an Identified CI Refuses to Take the Stand
A subpoena is a court order. A CI who has been identified and subpoenaed can be held in criminal contempt for refusing to appear or for refusing to answer questions, particularly after being granted immunity from prosecution.7U.S. Department of Justice. Criminal Resource Manual 780 – Direct Contempt Penalties can include fines and jail time until the witness complies.
From a defendant’s perspective, a CI who won’t testify is often good news. If the prosecution’s case leans on the informant’s involvement and that informant won’t take the stand, the court may strike related testimony, suppress evidence the CI helped gather, or allow negative inferences. Cases built around an uncooperative informant frequently collapse on their own.