Good-Faith Reliance on Cellphone Warrants with Minimal Nexus: The Second Circuit’s Guidance in United States v. Santos

Court: U.S. Court of Appeals for the Second Circuit (Summary Order)

Date: August 27, 2025

Case: United States v. Santos, No. 24-2301

Introduction

United States v. Santos is a Second Circuit summary order that addresses a recurring and consequential question in modern criminal investigations: when does the good-faith exception to the exclusionary rule save evidence obtained under a digital search warrant that lacks probable cause? The case arises from two alleged robberies of United States Postal Service (USPS) relay box keys—so-called “arrow keys”—in Brooklyn, New York. Tyrone Santos was later arrested, and agents obtained a warrant to search his smartphone seized at the time of arrest. The district court suppressed the phone evidence, finding that the affidavit failed to establish probable cause connecting the phone to the robberies and that the affidavit was so “bare bones” that officers could not rely on the warrant in good faith. The government appealed the good-faith ruling.

The Second Circuit vacated the suppression order and remanded, holding that even assuming a lack of probable cause (which the government did not contest on appeal), the affidavit was not so devoid of facts—i.e., not “bare bones”—as to render reliance on the warrant objectively unreasonable. Although the ruling is a nonprecedential summary order, it provides concrete guidance on how much factual nexus between a suspect’s phone and alleged crimes suffices to invoke the good-faith exception in the smartphone context.

Summary of the Judgment

The government appealed an interlocutory order suppressing evidence from Santos’s smartphone.
The government did not challenge the district court’s conclusion that probable cause was lacking; it argued only that the good-faith exception applied.
The Second Circuit reviewed the legal determination de novo and held that the affidavit was not “totally devoid” of facts linking the phone to the robberies.
Key facts in the affidavit included: a victim’s photo-array identification of Santos; surveillance showing a person identified as Santos on his phone in the vicinity approximately two hours before the first robbery; the affiant’s statement that the phone in the image matched Santos’s phone; and the inspector’s training-and-experience explanation that cellphones are commonly used to traffic or use stolen arrow keys and coordinate such crimes.
Given these facts, the warrant application, while not robust, was not so lacking in indicia of probable cause that reliance on it was unreasonable. The good-faith exception therefore applied.
The court vacated the suppression order and remanded for further proceedings.

Factual and Procedural Background

The affidavit alleged two robberies of USPS arrow keys, on September 30 and October 14, 2023. Arrow keys are universal keys that open USPS relay boxes, which may contain hundreds of mail items with items of potential value (e.g., cash, checks, gift cards, and identifying documents). Following a victim’s identification, Santos was arrested at his sister’s residence, and his phone was seized. Several days later, a postal inspector obtained a search warrant for the phone, supported by an affidavit that included:

Surveillance footage stills depicting an individual identified as Santos using a cellphone near the location of the first robbery, roughly two hours prior to that event.
An assertion that the phone seen in the surveillance matched Santos’s phone seized from the couch where he slept, and confirmation from his sister that the phone was his.
A training-and-experience paragraph explaining how stolen arrow keys are commonly trafficked and used in concert with cellphones to communicate with counterfeiters or co-conspirators and to surveil targets.
An inference that, because no arrow keys were recovered at Santos’s residence, he likely transferred or sold them, potentially using his phone.
Additional witnesses who identified Santos from video stills appended to the affidavit.

The warrant authorized a search for, among other items, text messages and call logs between the day before the first robbery and the date of arrest, location data for the same period, and photographs that might depict arrow keys or mail-related contraband.

The district court suppressed all phone evidence, holding that the affidavit lacked probable cause and was so “bare bones” that the good-faith exception could not apply. The government appealed only the good-faith question. The Second Circuit vacated the suppression ruling, concluding that the affidavit contained enough factual material to make reliance on the magistrate judge’s issuance of the warrant objectively reasonable.

Precedents Cited and Their Influence

United States v. Leon (U.S. 1984)

Leon is the foundation of the good-faith exception to the exclusionary rule. When officers rely on a warrant issued by a neutral magistrate, suppression is inappropriate if that reliance is objectively reasonable, even if the warrant is later found unsupported by probable cause. Leon recognizes limits: good faith does not apply if the affidavit is so lacking in indicia of probable cause that reliance is unreasonable, if the warrant is facially deficient, if the magistrate wholly abandons the judicial role, or if the affidavit contains knowingly false or recklessly misleading statements. Santos applies Leon’s central insight: officers generally may rely on a magistrate’s probable cause determination unless the application falls into one of those disqualifying categories.

United States v. Raymonda (2d Cir. 2015)

Raymonda clarifies standards of appellate review in suppression cases and the contours of good-faith analysis in the Second Circuit. Santos cites Raymonda for the standard of review—de novo for legal determinations, including probable cause and good faith—and for the framework that focuses on the objective reasonableness of reliance on a warrant. The court followed Raymonda to independently review the district court’s good-faith determination.

United States v. George (2d Cir. 1992)

George emphasizes that the burden is on the government to establish the objective reasonableness of reliance on a warrant. In Santos, the court expressly reiterates this allocation of the burden and then finds it satisfied because the affidavit’s factual content was not “totally devoid,” making reliance reasonable.

United States v. Silva (2d Cir. 2025)

Silva restates the exceptions to good faith: (1) where the application is so lacking in indicia of probable cause that reliance is unreasonable; and (2) where the warrant is so facially deficient that reliance is unreasonable. Santos quotes Silva and applies the first limitation, concluding the affidavit was not so deficient as to defeat good faith.

United States v. Clark (2d Cir. 2011)

Clark introduces the “totally devoid of factual circumstances” phrase, often associated with “bare bones” affidavits. Santos leans on Clark to differentiate between warrants supported by minimal factual content (which can still support good-faith reliance) and applications that are utterly conclusory. The court expressly says this case “falls somewhere in between” detailed affidavits and those with no facts at all, but it is not “bare bones.”

United States v. Falso (2d Cir. 2008)

Falso is a key analog: the Second Circuit applied good faith even after concluding the warrant lacked probable cause, because reasonable minds could differ on the probable-cause question. Santos invokes Falso to underscore that a close call on probable cause typically supports the reasonableness of reliance, and thus good faith applies.

Legal Reasoning

1) Standard of Review

Factual findings are reviewed for clear error.
Legal conclusions—including probable cause and good faith—are reviewed de novo, without deference to the district court’s reasoning.

2) The Government’s Narrow Appeal

On appeal, the government did not contest the district court’s conclusion that the affidavit lacked probable cause. The only question was whether the good-faith exception nevertheless permitted admission of the evidence. That posture is critical: the Second Circuit assumed arguendo there was no probable cause and asked whether the affidavit was so deficient that officers could not reasonably rely on the magistrate’s issuance of the warrant.

3) Why the Affidavit Was Not “Bare Bones”

The Second Circuit cataloged the affidavit’s factual content and found it sufficient to avoid the “bare bones” label:

Surveillance footage showed an individual identified as Santos using a phone near the scene about two hours before the first robbery.
The phone visible in the surveillance stills matched the phone seized from Santos’s residence and identified by his sister as his.
At least one victim identified Santos via a photo array; two additional witnesses identified him from the same surveillance stills appended to the affidavit.
The affiant’s training and experience explained how cellphones are commonly used to traffic, counterfeit, sell, or coordinate the use of arrow keys and to surveil when relay boxes can be targeted.
No arrow keys were found at Santos’s residence, supporting an inference he may have transferred or sold them—potentially using his phone.

Taken together, these facts provided some nexus between the phone and the suspected offenses. While the nexus may have been thin, it was not non-existent. That is enough, under Leon, Clark, and Falso, to render reliance on the magistrate’s decision objectively reasonable.

4) Emphasis on Magistrate Role and Reasonable Reliance

Echoing Leon, the court stressed the baseline rule: officers ordinarily may rely on a magistrate’s probable cause determination. The good-faith exception fails only when the affidavit is so conclusory or the warrant so facially deficient that reliance would be unreasonable. Here, because the affidavit contained a time-and-place connection between the suspect’s phone and the crime, plus specific investigative and identification details and an expert explanation of how phones figure in arrow key crimes, it crossed the minimal threshold.

5) The “Middle Ground” Affidavit

The court candidly acknowledged the affidavit “falls somewhere in between” a robust, detail-rich application and a truly “bare bones” one. That observation fortifies the holding: good faith is designed for precisely such “close call” scenarios. If reasonable jurists could disagree about whether the affidavit establishes probable cause, suppression is not warranted because the officers acted reasonably in relying on the warrant.

Impact and Implications

1) Digital Search Warrants and Minimal Nexus

Santos underscores a pragmatic threshold for good faith in the cellphone context. The court did not bless the affidavit as sufficient for probable cause; it assumed the opposite. But it held that:

Shortly pre-crime use of the phone in the vicinity,
Identification of the suspect by witnesses,
Match of the device in surveillance to the seized phone, and
Training-and-experience statements linking phones to the specific criminal scheme,

together can make reliance objectively reasonable. In future cases, prosecutors and agents can expect a similar analysis when a warrant’s nexus is modest but not purely speculative.

2) The High Bar for “Bare Bones”

The decision reinforces that “bare bones” means truly conclusory applications “totally devoid” of factual circumstances. If an affidavit contains concrete, case-specific facts connecting the device to the crime—even indirectly—and not merely boilerplate, good faith likely applies even when probable cause is debatable.

3) Practical Drafting Guidance for Law Enforcement

Include specific observations tying the phone to the offense (temporal and spatial proximity; observed use related to the criminal window).
Document witness identifications and attach corroborating visuals or stills where possible.
Articulate, based on training and experience, why phones are likely repositories of evidence for the particular crime—not just in general, but in this modus operandi.
Explain inferences logically (e.g., absence of physical items at residence suggests transfer or sale using the phone).
Tailor temporal scope and data categories (as was done here) to the suspected offense period and evidence sought; this bolsters reasonableness and mitigates overbreadth concerns.

4) Defense Strategy Considerations

To defeat good faith, focus on showing the affidavit is conclusory and lacks concrete, case-specific facts (i.e., truly “bare bones”).
Scrutinize misstatements or omissions that could trigger broader Leon limits (e.g., knowingly false statements or reckless disregard for truth), although those issues were not at play in Santos.
Consider whether the warrant is facially deficient (e.g., lacks particularity or is unbounded in scope) because such defects also negate good faith.
Even if probable cause is lacking, the remedy of suppression may be denied if the application presents some plausible nexus; defense must be prepared to meet the high bar for excluding evidence under good faith.

5) Institutional Note: Nonprecedential but Instructive

Because this is a summary order, it is not precedential. However, under FRAP 32.1 and the Second Circuit’s Local Rule 32.1.1, parties may cite it, and it will likely be persuasive in district courts addressing similar smartphone nexus questions. The order signals continued adherence to Leon and Falso in the digital evidence context: borderline affidavits often survive suppression via good faith where they contain some concrete link to the alleged crime.

Complex Concepts Simplified

Exclusionary Rule: A judicially created remedy that generally bars the government from using evidence obtained in violation of the Fourth Amendment.
Good-Faith Exception (Leon): Even if a warrant lacks probable cause, evidence need not be excluded if officers relied on the warrant in “objective good faith.” Notable limits include:
- Affidavit so lacking in indicia of probable cause that reliance is unreasonable (“bare bones”).
- Warrant so facially deficient (e.g., lacking particularity) that reliance is unreasonable.
- Magistrate wholly abandons the judicial role.
- Affidavit contains knowingly false statements or reckless disregard for the truth.
“Bare Bones” Affidavit: An application that is “totally devoid” of concrete factual circumstances and relies only on conclusory assertions. Such applications cannot support good-faith reliance.
Probable Cause vs. Good Faith: Probable cause asks whether a fair probability exists that evidence will be found in the place to be searched. Good faith asks whether, regardless of the ultimate existence of probable cause, officers acted reasonably in relying on the magistrate’s issuance of the warrant.
Interlocutory Appeal: An appeal filed before the final judgment in a case. The government may seek interlocutory review of suppression orders in criminal cases.
Summary Order: A nonprecedential decision by the Second Circuit that may be cited under specified rules but does not bind future panels.
Arrow Keys: Universal USPS keys used to access relay boxes containing large volumes of mail; because of their utility, they can be valuable to criminals involved in mail theft, fraud, and identity theft schemes.

What the Court Did Not Decide

The existence of probable cause. The government did not challenge the district court’s probable cause ruling, so the Second Circuit did not reach that question.
Any issue of particularity or overbreadth beyond noting that the warrant had defined temporal parameters and categories of data. No facial-deficiency finding was addressed on appeal.
Any claim of deliberate or reckless falsehoods in the affidavit or abandonment of judicial role; these were not asserted.

Conclusion

United States v. Santos reinforces a practical and familiar, yet vital, rule in the digital evidence era: when agents present an affidavit with some concrete, case-specific facts linking a suspect’s cellphone to the suspected crime—even if the nexus is modest—officers may ordinarily rely on a magistrate’s issuance of the warrant in good faith. The affidavit here was far from the ideal, and the district court found it lacked probable cause. Yet, because it was not “totally devoid” of factual support—combining identification evidence, surveillance showing phone use near the time and place of the first robbery, a match between the observed phone and the seized device, and an explanation of how phones commonly facilitate arrow key crimes—the Second Circuit held reliance was objectively reasonable.

For investigators and prosecutors, Santos offers a workable checklist for digital warrant affidavits: tie the device to the offense window, document the suspect’s use and possession of the device close in time to the crime, and explain why phones are likely repositories for the evidence of that particular crime. For the defense, the case underscores the high threshold for suppression under good faith—mere absence of probable cause may not suffice if the affidavit contains concrete, albeit thin, nexus facts. And for the courts, it is a reminder of Leon’s enduring framework: when reasonable minds can differ about probable cause, suppression is often unwarranted because the constitutional aim of deterrence is not served by penalizing objectively reasonable reliance on a magistrate’s decision.

Although nonprecedential, Santos will likely be cited as a persuasive reference in the Second Circuit for digital search warrants. Its signal is clear: in the smartphone context, the bar for “bare bones” remains high, and the good-faith exception is robust where affidavits contain some real-world, case-specific factual link between the device and the charged conduct.