Beyond the Evidence Table: First Circuit Re-Affirms Courts’ “Un-Flagging Duty” to Investigate Any Contact between a Deliberating Jury and an Adversary’s Case Agent

1. Introduction

United States v. Matta-Quiñones, decided by the First Circuit on 9 June 2025, vacates two firearm convictions and a supervised-release revocation because the trial judge permitted the government’s lead case agent to stand beside jurors and hand them guns and ammunition during deliberations, yet undertook no inquiry into possible juror taint.

While the panel (Judges Montecalvo, Thompson, and Aframe, opinion by Judge Thompson) rejected the defendant’s sufficiency-of-the-evidence challenge, it held that the district court’s failure to investigate a “colorable claim of juror misconduct” constituted reversible error. The ruling clarifies three doctrinal areas:

The scope of a trial court’s mandatory inquiry when there is any plausible allegation that outside influence reached the jury.
The limits on allowing a prosecution-affiliated individual to assist jurors with evidence once deliberations have begun.
Practical guidance on double hearsay within business records and on using FBI FD-302 reports for impeachment—issues addressed to forestall repetition at any retrial.

2. Summary of the Judgment

The panel affirmed that the government presented sufficient evidence to allow a reasonable jury to convict on both counts (§ 922(g) and § 922(o)).
It nevertheless vacated the convictions and supervised-release sentence because the district court violated the Sixth-Amendment guarantee of an impartial jury by (a) placing the government’s case agent with the jurors during deliberations and (b) refusing to conduct any inquiry afterwards.
The First Circuit remanded for a new trial and for re-sentencing on the non-firearm “technical” supervised-release violations.
Two evidentiary holdings—concerning an FBI Form 302 and a Probation “Receipt for Property” form—were flagged as abuses of discretion likely to recur.

3. Analysis

3.1 Precedents Cited and Their Influence

The Court wove together precedents on juror contact, jury secrecy, and the duty of inquiry:

Remmer v. United States, 347 U.S. 227 (1954) – classic source of the duty to probe allegations of outside influence.
United States v. Olano, 507 U.S. 725 (1993) – privacy of deliberations and standards for “intruders” in jury rooms.
United States v. Paniagua-Ramos, 251 F.3d 242 (1st Cir. 2001) – coined the phrase “un-flagging duty” to investigate juror misconduct.
United States v. Gastón-Brito, 64 F.3d 11 (1st Cir. 1995) – reversed where the case agent made a gesture toward jurors without proper judicial inquiry.
Ninth, Sixth and Tenth Circuit analogues (United States v. Pittman, 449 F.2d 1284; United States v. Florea, 541 F.2d 568; United States v. Freeman, 634 F.2d 1267) — all critical of allowing a prosecution agent in a “friend-of-the-jury” role.

Together, these cases framed the doctrinal baseline: any credible suggestion that an adversary has had private contact with deliberating jurors triggers a mandatory “adequate inquiry.” The panel relied heavily on Gastón-Brito and Paniagua-Ramos to emphasize that the district court has no discretion to do nothing.

3.2 The Court’s Legal Reasoning

Preservation. The First Circuit ruled that defense counsel’s repeated objections (asking either to keep the agent away or let the evidence go to the jury room instead) preserved the issue. The district court’s stance (“don’t make a federal case out of it”) foreclosed further protest, preventing waiver.
Colorable Claim of Misconduct. The panel held that placing a known member of the prosecution team in close proximity to jurors while they handled exhibits—after formal deliberations had begun—presented a non-frivolous risk of undue influence. The risk was exacerbated because the judge endowed the agent with a quasi-bailiff role (“hand the weapon to the jury”), blurring adversarial lines.
Mandatory Inquiry. Once that risk surfaced, the district court had an “un-flagging duty” to investigate. Its outright refusal, and reliance solely on its own assumption that the agent “kept his mouth shut,” constituted reversible error.
No Harmless-Error Escape. Because no inquiry occurred, the record was devoid of facts showing harmlessness. The Court declined to presume lack of prejudice; instead, it followed the logic of Pittman: uncertainties about unseen influence require a new trial.
Local Rule Cannot Trump the Constitution. The judge referenced D.P.R. Local Rule 123 (weapons stay with the investigative agency), but the panel said local administrative rules cannot override a defendant’s constitutional right to an impartial jury.

3.3 Impact on Future Practice

Bright-line guidance: Trial courts in the First Circuit must either (a) bar adversary agents from direct contact with deliberating juries, or (b) upon any contact, conduct an immediate and tailored inquiry (voir dire, hearing, written affidavits, etc.).
Case-agent logistics: Prosecutors will need neutral custodians (e.g., CSOs) to handle sensitive exhibits once jurors retire. Integrating local rules with constitutional safeguards may prompt district courts to amend evidence-handling protocols.
Appellate preservation clarified: Counsel need not deliver a “perfect” objection; context and repeated efforts can suffice when a judge signals a firm decision.
Evidentiary rulings preview: The Court’s dicta on FD-302 impeachment and business-records double hearsay will guide trial strategy in Puerto Rico and throughout the Circuit.

4. Complex Concepts Simplified

Colorable Claim of Juror Misconduct: A credible, non-speculative allegation that something occurred which could influence the jury’s impartiality.
Case Agent: The lead law-enforcement officer assigned to work with prosecutors; typically sits at counsel table and manages evidence.
FD-302: The FBI’s standard form memorialising witness interviews. Unless the witness adopts or signs it, the form itself is the agent’s statement, not the witness’s.
Business-Records Exception (Rule 803(6)): Allows admission of regularly kept records if (i) made contemporaneously, (ii) by someone with knowledge, (iii) as part of regular business activity. Multiple hearsay inside the record is admissible only if each layer meets an exception or shows equivalent “indicia of reliability.”
“Un-Flagging Duty”: The appellate shorthand for a trial court’s obligation to investigate any plausible threat to jury impartiality; the duty is mandatory, not discretionary.

5. Conclusion

United States v. Matta-Quiñones powerfully restates that the appearance of impartiality is as crucial as its reality. By converting a prosecution agent into a de-facto court officer, the trial judge created precisely the sort of ambiguity that the Sixth Amendment forbids and then compounded the problem by declining to explore what happened. The First Circuit’s remedy—a new trial—is a cautionary tale: when adversaries approach the jury room door, the court must either keep that door firmly shut or open another one—the door to rigorous inquiry. Going forward, defenders, prosecutors, and judges alike have clearer lines: protect the sanctity of deliberations, document chains of custody without adversary chaperones, and remember that even well-intentioned procedural shortcuts can unravel an entire verdict.