United States v. Castillo: No Outrageous Misconduct for U.S.-Led Foreign Arrests; Pen Register Metadata Is Non‑Hearsay

Introduction

In United States v. Castillo, the First Circuit affirmed the conviction and 300-month sentence of Fermin Castillo for conspiracy to distribute fentanyl and conspiracy to commit money laundering. The court rejected a wide array of challenges spanning pretrial dismissal, evidentiary rulings, claims of prosecutorial misconduct, jury instructions, and sentencing. Two doctrinal clarifications stand out:

• The participation of U.S. law enforcement in a foreign arrest—without advance Department of Justice approval and allegedly in tension with the Mansfield Amendment—does not, standing alone, constitute “outrageous government misconduct” warranting dismissal of an indictment.
• Pen register records are non-hearsay machine-generated data and are admissible without resort to the business-records exception, so long as the dataset reflects automatic provider output rather than human assertions.

The case arose from a Boston-based fentanyl operation (2019–2021) associated with a stash location at 800 Hyde Park Avenue and vehicles outfitted with hidden compartments. Though Castillo largely directed the operation from Mexico via WhatsApp, he periodically assisted in Boston. After searches uncovered multiple kilograms of fentanyl and seizure of currency (including $150,000 from a hidden compartment), a jury convicted Castillo on both conspiracy counts. He received concurrent terms, the longest of which was 25 years. A cooperating co-defendant, Cesar Castro, later received a 39-month sentence, a disparity Castillo raised on appeal.

Summary of the Opinion

Judge Montecalvo, writing for a panel that included Chief Judge Barron and Judge Rikelman, affirmed across the board:

• Pretrial dismissal: Even assuming U.S. Marshals effected a foreign arrest without DOJ “advance approval,” that does not “shock the universal sense of justice” so as to require dismissal. Neither an alleged Mansfield Amendment violation nor internal DOJ policy noncompliance suffices.
• Evidentiary rulings: Challenges to prior-acts evidence, pen register data, a $1,000 transfer to Sinaloa, and alleged “overview” testimony failed under abuse-of-discretion or plain-error review, often as harmless or waived. The court squarely treated pen register metadata as non-hearsay machine output.
• Prosecutorial misconduct: Minor misstatements in opening and closing did not amount to plain error or prejudice in light of instructions and the strength of the case.
• Jury instructions: Although the money laundering instruction omitted the interstate/foreign commerce element (§ 1956(c)(4)), the appellant waived plain-error relief by not demonstrating effects on substantial rights or the fairness of proceedings.
• Sentencing: The “stash house” enhancement was supported; an Apprendi/Alleyne objection based on use of “fentanyl” rather than its chemical name was waived; the significant disparity with Castro’s later sentence was not an abuse of discretion given materially different postures (plea and cooperation) and Castillo’s below-Guidelines sentence.

Analysis

Precedents Cited and Their Influence

• Outrageous Government Misconduct:
  • United States v. Luisi and United States v. Therrien provide the First Circuit’s high bar: only conduct that “shocks the universal sense of justice” suffices, e.g., when agents engineer a crime from start to finish, misuse sexual relationships as investigative tools, or physically/psychologically abuse defendants.
  • United States v. Anzalone: The First Circuit has never reversed on this ground; Castillo is not the first.
  • United States v. Alvarez‑Machain (U.S. Supreme Court): A defendant forcibly kidnapped abroad at DEA direction still could be tried in U.S. court; that authority undercuts the argument that agent participation in foreign arrests necessarily defeats jurisdiction or due process.
  • United States v. Twigg (3d Cir.): Offers a rare example of “outrageous” conduct (government supplied essential ingredients, know‑how, and lab for drug manufacture). Castillo’s alleged arrest‑protocol violation falls far short.
• Pen Register Metadata and Hearsay:
  • Multiple circuits treat machine‑generated data as non‑hearsay because it is not a “statement” by a human “declarant” (e.g., Miller (6th), Channon (10th), Lizarraga-Tirado (9th), Washington (4th), Lamons (11th)). The First Circuit aligned with this consensus here.
  • Benavente Gomez and Moore (1st Cir.): Distinguished. Where underlying entries are made by humans (loan histories), hearsay analysis applies; but automatically generated data (pen registers) are qualitatively different.
• Preservation and Trial Management:
  • Perez‑Delgado, Soto‑Soto, Rivera‑Berríos, and Villa‑Guillen: Preservation does not require “exquisite precision.” Given a judge’s bar on speaking objections, the First Circuit will look to context and what the trial court understood. The panel also honored the trial judge’s instruction that “the objection of one defendant is the objection of both” (see Sepulveda), attributing a co‑defendant’s objections to Castillo.
  • Plain‑error backstop remains stringent (Encarnacion, Duarte, Madsen).
• Evidentiary Standards:
  • Rule 404(b) and Rule 403 framing follows First Circuit practice (Henry, Soler‑Montalvo), with the court noting “mutual trust” among co‑conspirators as a permissible 404(b) purpose (Weadick).
  • Harmless‑error review invoked where potential missteps existed (Lucy, Morgan), underscoring the weight of corroborated evidence against Castillo.
• Prosecutorial Argument:
  • Opening statements are roadmaps, not evidence; an incorrect prediction requires proof of bad faith to warrant relief (Frazier, Cruz).
  • For closing arguments, misstatements are measured for prejudice in context (Madsen, Azubike, Joyner, Vázquez‑Larrauri, Kasenge).
  • Community‑conscience appeals are improper, but the remarks here were a far cry from prior reversals (Canty, Avilés‑Colón).
• Jury Instructions and Plain Error:
  • Interstate/foreign commerce is an element of § 1956. The omission was “clear or obvious,” but plain error was waived absent any showing on substantial rights or fairness (Andino‑Rodríguez, Cruz‑Ramos, Velázquez‑Aponte).
• Apprendi/Alleyne and Sentencing Law:
  • Apprendi/Alleyne principles were invoked to argue a mismatch between “fentanyl” in the verdict and the chemical name in § 841(b)(1)(A)(vi). The court deemed the argument waived given the record’s consistent use of “fentanyl” without objection (Pizarro).
  • Guidelines review applied familiar standards (Aponte‑Colon, Polaco‑Hance, Gall), including enhancement proof by preponderance (González‑Santillan).
  • Disparity claims under § 3553(a)(6) focus on national disparities, and drastically different codefendant sentences do not compel relief when defendants are materially dissimilar—such as where one pleads and cooperates and the other goes to trial (Bishoff, Candelario‑Ramos, Rodriguez‑Lozada).
  • Substantive reasonableness is reviewed for defensible rationales within a broad range of reasonable outcomes; below‑Guidelines sentences are rarely found unreasonable (Concepcion‑Guliam, Millán‑Machuca, Floyd, Reyes‑Santiago, Rossignol, Reverol‑Rivera).

Legal Reasoning: How the Court Reached Its Conclusions

• Outrageous Government Misconduct: The court assumed that U.S. Marshals made the foreign arrest without DOJ “advance approval,” yet emphasized that even forcible abductions have not defeated jurisdiction (Alvarez‑Machain), and alleged Mansfield Amendment or policy violations do not meet the “outrageous” threshold. The decision positions protocol breaches as far removed from the paradigms of due‑process “shock.”
• Rule 404(b) and Rule 403: Pre‑period conduct was limited and, where arguably admitted in error, was harmless against a robust body of direct and circumstantial evidence. Evidence of earlier dealings also had a non‑propensity purpose (co‑conspirator trust).
• Pen Register Metadata: The court accepted testimony that providers automatically generated dialed/received numbers, timestamps, and related metadata that DEA systems ingested. Because no human asserted anything within the dataset, Rule 801’s hearsay bar did not apply; no business‑records predicate was needed for the provider output itself. Any inconsistency in sub‑exhibits was harmless, given admitted master datasets and the absence of reliance on subsets in argument.
• Wire Transfer to Sinaloa: The defense’s relevance-only objection did not preserve unfair-prejudice grounds; the plain-error claim was a bare, undeveloped assertion and thus waived.
• “Overview” Testimony: The challenged snippets were either elicited on cross, grounded in personal knowledge, or clarified by the judge. Use of “we” by a co‑case agent who personally investigated did not inject vouching or lay opinions of guilt.
• Prosecutorial Misconduct: The government’s opening and closing were mostly tethered to the proof. A handful of misstatements—such as referencing stricken testimony about a phone number—were minor and non-prejudicial, particularly in light of the court’s repeated instructions that arguments are not evidence and the strength of the record (e.g., WhatsApp coordination, in‑person assistance, undercover money-laundering pickups paid out in Mexico, stash-house seizures, and hidden-compartment currency).
• Jury Instruction (Money Laundering): While omitting commerce was error, Castillo did not satisfy the third and fourth plain-error prongs. The court refused to find plain error sua sponte without an articulated showing of prejudice or injury to the integrity of the proceedings.
• Sentencing:
  • Apprendi/Alleyne: A semantics challenge to using the common word “fentanyl” rather than the statutory chemical name was waived, particularly given the trial’s unobjected-to usage of “fentanyl” from opening through verdict.
  • Stash-house enhancement: Evidence supported that Castillo maintained 800 Hyde Park Ave. (keys, lease, usage for distribution). The jury even found this beyond a reasonable doubt on a special interrogatory, bolstering the preponderance finding for the enhancement.
  • Disparity: The 261-month spread with Castro’s later 39-month sentence did not render Castillo’s 300-month, below-Guidelines sentence unreasonable. Plea/cooperation materially distinguished Castro; § 3553(a)(6) concerns primarily national uniformity, not automatic parity among co-defendants.

Impact: Why This Opinion Matters

• Cross‑border arrests: Defense efforts to convert alleged violations of the Mansfield Amendment or internal DOJ policy into due‑process dismissals face extremely long odds. The court cabined “outrageous” claims to truly egregious scenarios, reinforcing prosecutors’ ability to proceed even if arrest protocols are later disputed.
• Digital evidence foundations: The ruling will ease admission of pen register metadata in the First Circuit by classifying it as non-hearsay machine output. Practitioners should focus on proving that the data are automatically generated by a provider system, not human-entered.
• Preservation in tightly managed trials: When judges forbid speaking objections, the First Circuit will reconstruct the basis of objections from context and treat co-defendant objections as shared. Still, parties should use motions in limine, proffers, and post‑sidebar clarifications to ensure a clear record.
• Openings and closings: The decision confirms that modest misstatements, absent bad faith or prejudice, rarely warrant reversal—especially with curative instructions and strong evidence.
• Jury instructions and plain error: Even a conceded error on an element (here, § 1956 commerce) will not yield relief without a concrete showing on substantial rights and the fairness of proceedings. Appellants should be prepared to explain how the error plausibly affected the verdict.
• Sentencing disparities: Large co-defendant disparities will not compel reversal where differences in plea posture and cooperation exist, and where the challenged sentence is itself a meaningful downward variance from a properly calculated range.

Complex Concepts Simplified

• Outrageous Government Misconduct: A due‑process safety valve that permits dismissal only when government behavior is so extreme that it offends fundamental justice (e.g., creating a crime from scratch or abusing a defendant). Mere procedural irregularities in an arrest, especially overseas, almost never qualify.
• Mansfield Amendment (22 U.S.C. § 2291(c)): A statute restricting U.S. officers’ direct law‑enforcement roles abroad. Alleged violations do not automatically translate into constitutional violations that dismiss criminal charges.
• Pen Register: A tool that captures dialed/received numbers and metadata (dates/times), not call content. Because the provider’s systems generate this data automatically, it is not hearsay (no human “declarant”).
• Rule 404(b): Generally bars prior bad acts to show propensity, but allows them for non‑propensity purposes (e.g., intent, plan, identity, or trust among co-conspirators). Even then, Rule 403 balancing can exclude unduly prejudicial material.
• Harmless Error vs. Plain Error: Harmless-error review asks whether an error likely affected the outcome; plain error requires an appellant to show a clear error that affected substantial rights and seriously undermined the proceedings’ integrity—without a timely objection, that is a heavy lift.
• “Stash‑house” Enhancement (U.S.S.G. § 2D1.1(b)(12)): Adds two levels if a defendant “maintained” premises for distribution. Evidence like keys, leases, and usage for drug activity can satisfy this standard.
• Sentencing Disparity (§ 3553(a)(6)): Focuses on avoiding unwarranted national disparities. Codefendants can properly receive very different sentences where one pleads and cooperates and the other proceeds to trial.
• Apprendi/Alleyne: Facts that raise statutory maximums or mandatory minimums must be found by a jury beyond a reasonable doubt. But semantic quibbles (here, using “fentanyl” versus the chemical name) must be preserved and are unlikely to prevail when the record consistently uses the common term.

Conclusion

United States v. Castillo is an across-the-board affirmance that nonetheless advances several clarifications with broad practical relevance. First, it reinforces the narrowness of the “outrageous government misconduct” doctrine and clarifies that alleged deviations from foreign-arrest protocols or DOJ policies do not automatically trigger dismissal. Second, it places the First Circuit firmly with sister circuits that categorize pen register metadata as non-hearsay machine output. The opinion also offers pragmatic guidance on preservation in trials where speaking objections are curtailed, underscores the demands of plain-error review (particularly for omitted elements), and reaffirms that cooperation-based disparities are not inherently unreasonable—especially where the challenged sentence is a substantial downward variance.

For investigators and prosecutors, Castillo supports robust use of metadata evidence and maintains confidence in cross-border arrest outcomes. For defense counsel, it flags the need to preserve element-based objections at trial, to articulate concrete prejudice under plain-error standards, and to anticipate that cooperating co-defendants may receive dramatically lower sentences without creating reversible disparities. Overall, the opinion aligns First Circuit practice with prevailing national standards while offering case-management guidance that will shape how complex conspiracy trials are tried and reviewed.