Law Enforcement Electronic Surveillance Defense

In-depth analysis of how state and federal law enforcement use CSLI, geofence and Flock/ALPR surveillance, and recording devices in Tennessee - with Sixth Circuit and Tennessee case law, the geofence circuit split, the good-faith exception, and concrete ways to challenge the legality and sufficiency of a warrant.

Challenging Law Enforcement Electronic Surveillance in Tennessee

Modern criminal investigations increasingly rely on electronic surveillance. State and federal agencies use a growing array of technology to build cases—cell phone location data, networked cameras, license plate readers, audio and video recording, and more. When the government relies on this evidence, the central question for the defense is whether it was gathered lawfully. Surveillance that violates the Fourth Amendment, article I, section 7 of the Tennessee Constitution, or applicable statutes can often be challenged, and evidence obtained unlawfully may be suppressed.

This page provides an in-depth look at the surveillance methods used in Tennessee state and federal prosecutions, the controlling and persuasive case law—including United States Supreme Court precedent, decisions of the United States Court of Appeals for the Sixth Circuit (which governs federal cases in Tennessee), federal district court rulings, and Tennessee Supreme Court and Court of Criminal Appeals decisions—and the concrete ways a defense attorney can attack the legality and sufficiency of a warrant. It is written to inform, not to substitute for advice about a specific case.

A Note on Jurisdiction: Why the Forum Matters

Where a case is prosecuted shapes which law controls. A Tennessee state prosecution is governed by the Fourth Amendment, article I, section 7 of the Tennessee Constitution, Tennessee statutes, and the Tennessee Rules of Criminal Procedure, with the Tennessee Supreme Court and Court of Criminal Appeals as the controlling courts. A federal prosecution in Tennessee—brought in the Eastern, Middle, or Western District—is governed by the Fourth Amendment and the Federal Rules, with the Sixth Circuit as the controlling appellate court and United States Supreme Court precedent binding on all.

This distinction matters because the Tennessee Constitution can, in principle, provide protections independent of the federal floor, and because federal district courts within the Sixth Circuit sometimes reach differing conclusions on unsettled questions until the Court of Appeals or Supreme Court resolves them. Decisions from other circuits are not binding in Tennessee, but they are frequently cited as persuasive authority—and on fast-moving questions like geofence warrants, those out-of-circuit splits often drive the argument.

Surveillance Methods and Devices Used to Build Cases

Cell Site Location Information (CSLI)

Every time a cell phone connects to a tower, it generates time-stamped location data stored by the wireless carrier. Investigators use historical CSLI to place a person near a location over days, weeks, or months. In Carpenter v. United States, 585 U.S. 296 (2018), the Supreme Court held that acquiring historical CSLI is a search that ordinarily requires a warrant supported by probable cause, and that the third-party doctrine of Smith v. Maryland and United States v. Miller does not automatically defeat the privacy interest in long-term location data. The case originated in the Sixth Circuit, which had held the opposite before being reversed.

The deeper lesson of Carpenter for Tennessee practitioners lies in what happened next, and that is discussed in the good-faith section below. Carpenter also expressly left open several questions: it did not decide real-time CSLI, “tower dumps” (records of every device that connected to a site during a window), or how short a span of CSLI triggers the warrant requirement. Those gaps are where much of the current litigation lives.

Cell Phone Data, Device Searches, and Geofence Warrants

Beyond location data, agencies extract call logs, messages, app data, photographs, and GPS history directly from devices. Under Riley v. California, 573 U.S. 373 (2014), police generally must obtain a warrant before searching the contents of a cell phone seized incident to arrest, given the immense quantity of private information a modern phone holds.

“Geofence” warrants—which ask a provider such as Google to identify every device present in a defined area during a window of time—are among the most contested tools in current Fourth Amendment law, and the federal courts are split. The point-by-point discussion of that split appears in the case law section below. For now, the practical takeaway is that the validity of geofence-derived evidence is an open and actively litigated question, and an unsettled area is precisely where a motion to suppress can have traction.

Automated License Plate Readers (ALPRs) and Flock Cameras

Automated license plate readers—including widely deployed Flock Safety camera networks—photograph passing vehicles, capture license plates, and log time and location in searchable databases. Agencies use this data to track vehicle movements and establish presence near a scene. Courts have generally upheld limited, fixed-location ALPR use against Fourth Amendment challenges, reasoning that a single photograph of a plate in public view does not invade a reasonable expectation of privacy. The emerging argument—modeled directly on Carpenter—is that a dense network of cameras with long data retention can aggregate into the kind of pervasive tracking that does require a warrant. This area is unsettled, fast-moving, and varies sharply by jurisdiction; the recent decisions are discussed below.

Pole Cameras, Surveillance Cameras, and Recording Devices

Police use fixed “pole cameras,” covert cameras, and audio recording devices to monitor activity over extended periods. Long-term pole-camera surveillance of a home has produced its own divide in the federal courts, with some judges treating months of continuous recording as a Carpenter-style search and others holding that recording what is visible from a public vantage point is not. Wiretaps and the interception of communications are separately governed by strict state and federal statutes, including the federal Wiretap Act (Title III) and Tennessee’s wiretapping statutes, and require specific, heightened authorization. Improperly authorized or executed interceptions can be suppressed under those statutes independent of the constitutional analysis.

GPS Tracking and Other Location Tools

In United States v. Jones, 565 U.S. 400 (2012), the Supreme Court held that physically attaching a GPS device to a vehicle to track its movements is a Fourth Amendment search. The concurrences in Jones—particularly Justice Alito’s and Justice Sotomayor’s discussion of long-term aggregated tracking—laid the intellectual groundwork for Carpenter and remain central to arguments about newer aggregation technologies like ALPR networks.

Foundational Case Law

A body of constitutional case law governs how and when these tools may be used. The foundational decisions, binding in every Tennessee court, include:

  • Katz v. United States, 389 U.S. 347 (1967). Established that the Fourth Amendment protects a reasonable expectation of privacy, not merely physical spaces—the foundation of modern surveillance law and the source of the familiar two-part “reasonable expectation of privacy” inquiry.
  • United States v. Jones, 565 U.S. 400 (2012). Attaching a GPS device to a vehicle to track its movements is a search; revived the property-based “trespass” theory alongside the Katz expectation-of-privacy test.
  • Riley v. California, 573 U.S. 373 (2014). Police generally must obtain a warrant before searching the digital contents of a cell phone seized incident to arrest.
  • Carpenter v. United States, 585 U.S. 296 (2018). Obtaining historical CSLI is a search ordinarily requiring a warrant; the third-party doctrine does not automatically apply to comprehensive digital location records.
  • Kyllo v. United States, 533 U.S. 27 (2001). Using sense-enhancing technology not in general public use to gather information from inside a home is a search.
  • Illinois v. Gates, 462 U.S. 213 (1983). Probable cause is judged under a “totality of the circumstances” test—the governing standard for evaluating warrant affidavits, including those resting on informant tips.
  • Franks v. Delaware, 438 U.S. 154 (1978). A defendant may challenge the truthfulness of a warrant affidavit and, on a sufficient showing, obtain a hearing that can void the warrant.

The Sixth Circuit and Federal District Courts in Tennessee

For a federal case in Tennessee, Sixth Circuit precedent controls. Several threads of that case law are especially important to surveillance litigation.

Carpenter on remand: the good-faith problem

After the Supreme Court’s reversal, the case returned to the Sixth Circuit as United States v. Carpenter, 926 F.3d 313 (6th Cir. 2019). The court affirmed the conviction anyway, holding that even though a warrant should have been obtained, the FBI agents had relied in objectively reasonable good faith on the Stored Communications Act, 18 U.S.C. § 2703(d), when they sought the records. The evidence was therefore admissible under the good-faith exception of United States v. Leon, 468 U.S. 897 (1984), and Illinois v. Krull, 480 U.S. 340 (1987) (good-faith reliance on a statute). This is the crucial practical lesson: establishing that a search was unconstitutional is only half the battle. The defense must also overcome the good-faith exception, which is frequently the government’s strongest response to a suppression motion involving novel technology.

Why district courts within the circuit can diverge

On questions the Sixth Circuit and Supreme Court have not squarely resolved—the precise threshold at which a short span of CSLI becomes a search, the treatment of tower dumps, real-time location pings, prolonged pole-camera surveillance, and ALPR aggregation—district courts in the Eastern, Middle, and Western Districts of Tennessee are free to reason to differing conclusions, and judges across the circuit have. Nationally, courts have divided over whether weeks or months of pole-camera footage of a residence is a Carpenter search; some suppress, others do not. These divisions are not a weakness in a suppression motion—they are the opening. An unresolved question lets the defense argue from first principles, marshal the more favorable district court and out-of-circuit opinions as persuasive authority, and frame the issue for appeal.

The Geofence Warrant Circuit Split

Geofence warrants illustrate how an out-of-circuit split becomes a live argument in Tennessee. The two leading federal appellate decisions reached opposite conclusions:

  • United States v. Chatrie, 4th Cir. (2024). The Fourth Circuit concluded that obtaining a limited window of Google Location History was not a Fourth Amendment search at all, reasoning that the user had opted in to location tracking and so the third-party doctrine applied.
  • United States v. Smith, 110 F.4th 817 (5th Cir. 2024). The Fifth Circuit reached the opposite result, holding that geofence warrants are “modern-day general warrants” categorically prohibited by the Fourth Amendment because they direct an open-ended, suspicionless search of an entire database before any suspect is identified—yet still admitted the evidence under the good-faith exception.

The split has drawn Supreme Court attention, and the Court agreed to take up the geofence question, so the law may change. Until the Sixth Circuit or the Supreme Court resolves it, a Tennessee defendant whose case rests on geofence data can argue the Smith “general warrant” theory—both that the warrant lacked particularity and that it authorized exactly the exploratory rummaging the Fourth Amendment forbids—while anticipating the government’s good-faith and Chatrie third-party responses. Because the area is genuinely unsettled, the current status of any pending Supreme Court decision should always be checked before relying on these authorities.

Tennessee State Law: Article I, Section 7 and the Good-Faith Exception

In a Tennessee state prosecution, two features of state law are especially important.

The state constitution and statutory warrant requirements. Article I, section 7 of the Tennessee Constitution protects against unreasonable searches and seizures in language that echoes the Fourth Amendment, and Tennessee courts construe it independently. A Tennessee search warrant must also satisfy statutory and rule-based requirements—including the affidavit and signature requirements of Tennessee Code Annotated §§ 40-6-103 and 40-6-104 and Tennessee Rule of Criminal Procedure 41. Historically, a defect in those requirements could require suppression even where the federal Constitution might not.

Tennessee’s good-faith exception. For many years Tennessee did not recognize a good-faith exception to its exclusionary rule. That changed in State v. Reynolds, 504 S.W.3d 283 (Tenn. 2016), where the Tennessee Supreme Court adopted a narrow good-faith exception modeled on Davis v. United States, 564 U.S. 229 (2011), allowing evidence obtained in objectively reasonable reliance on binding appellate precedent that is later overruled. In State v. Davidson, 509 S.W.3d 156 (Tenn. 2016), the court recognized a further good-faith exception where an officer complied with constitutional requirements but, in good faith, failed to satisfy a state statutory or rule-based affidavit requirement (there, a missing signature). A defense attorney litigating a Tennessee suppression motion must therefore anticipate a good-faith argument and be prepared to show that the asserted reliance was not objectively reasonable, or that the defect was constitutional rather than merely technical. Because the contours of the Tennessee exception continue to develop, the most current decisions should always be consulted.

How to Challenge the Legality and Sufficiency of a Warrant

Most surveillance evidence depends on a warrant, and the validity of that warrant is often the heart of the defense. The following are concrete, recognized lines of attack. Which apply depends entirely on the facts, and they are frequently raised together.

1. Attack probable cause within the four corners of the affidavit

A reviewing court ordinarily evaluates probable cause from the “four corners” of the affidavit under the totality-of-the-circumstances test of Illinois v. Gates. The defense argues that, even taking the affidavit at face value, the facts do not establish a fair probability that evidence of a crime will be found in the place to be searched. Common sub-arguments include conclusory or boilerplate assertions, a missing nexus between the alleged crime and the specific place or device, and reliance on innocent facts dressed up as suspicious.

2. Challenge staleness

Probable cause must exist at the time the warrant issues. Where the affidavit relies on old information—dated observations, a months-old tip, historical data with no recent corroboration—the defense argues the probable cause has gone stale. Staleness arguments are especially potent with historical digital data, where the government may seek long periods of records on thin recent justification.

3. Attack particularity and overbreadth

The Fourth Amendment and article I, section 7 require a warrant to describe with particularity the place to be searched and the things to be seized. Digital warrants are vulnerable here: a warrant authorizing seizure of an entire phone or “all data” can be challenged as an unconstitutional general warrant, and geofence and tower-dump warrants are attacked on precisely this ground—that they authorize a suspicionless search of many people’s data. The Smith “general warrant” reasoning is the model for this argument.

4. File a Franks motion for false statements or material omissions

Under Franks v. Delaware, a defendant who makes a substantial preliminary showing that the affiant included a deliberate falsehood, or acted with reckless disregard for the truth, is entitled to an evidentiary hearing. If, setting the false statement aside, the remaining affidavit no longer supports probable cause, the warrant is voided and the evidence suppressed. Courts have extended Franks to material omissions—facts the affiant deliberately or recklessly left out that, if included, would defeat probable cause. A Franks challenge requires more than conclusory contradiction; it demands a specific offer of proof, such as witness declarations or documentary evidence.

5. Challenge the reliability of an informant’s tip

Where probable cause rests on a confidential informant, the defense scrutinizes the informant’s veracity, reliability, and basis of knowledge under Gates, and whether police independently corroborated the tip. An anonymous or first-time informant with no track record, no corroboration, and no stated basis of knowledge may be insufficient. (Tennessee courts continue to draw on the Aguilar-Spinelli framework’s concerns even within the broader Gates totality analysis.)

6. Attack the execution of the warrant

Even a valid warrant can be executed unlawfully—searching beyond its scope, seizing items not described, ignoring time limits, or failing to follow knock-and-announce and return requirements. Evidence seized outside the warrant’s authorization may be suppressed.

7. Challenge statutory and rule compliance (Tennessee state cases)

In Tennessee state court, the affidavit, signature, and procedural requirements of Tennessee Code Annotated §§ 40-6-103 and 40-6-104 and Rule 41 provide an independent basis for challenge—subject, after Davidson, to the state’s good-faith exception for technical defects.

8. Argue no warrant where one was required

Where the government proceeded without a warrant—for example, obtaining historical CSLI under a § 2703(d) order rather than a warrant, conducting a warrantless phone search, or relying on a claimed exception—the defense argues a warrant was required and no exception applies. Here the analysis turns to Carpenter, Riley, and the recognized warrant exceptions, and to defeating the government’s good-faith fallback.

Overcoming the Good-Faith Exception

Because the good-faith exception is so often dispositive—as Carpenter on remand and Smith both show—a serious suppression strategy plans for it from the start. Leon itself identifies situations where good faith does not save a search: where the affidavit is so lacking in probable cause that no reasonable officer could rely on it (“bare bones”), where the magistrate was misled by a Franks-type falsehood, where the magistrate wholly abandoned the neutral role, or where the warrant is so facially deficient that reliance is unreasonable. The defense aims to fit the facts within one of these categories, or to show that there was no binding precedent or statute on which the officer could have reasonably relied. In Tennessee state court, the inquiry is whether reliance fell within the narrow Reynolds and Davidson exceptions at all.

The Exclusionary Rule and Its Reach

When a court suppresses evidence, the exclusionary rule can also reach evidence derived from the unlawful search—the “fruit of the poisonous tree.” The government may respond with doctrines that limit the rule’s reach: independent source, inevitable discovery, and attenuation. Effective suppression litigation anticipates these responses and addresses them directly, because excluding the primary evidence is often only the first step toward excluding everything that flowed from it.

Sufficiency of the Warrant: Putting It Together

In practice, a thorough warrant challenge proceeds on several fronts at once: testing probable cause within the four corners, probing for staleness and lack of nexus, attacking particularity, developing a Franks record where the facts support it, scrutinizing informant reliability, examining execution, and—in state court—checking statutory compliance, all while building the argument against good faith. The strongest motions are specific and factual, not generic, and they preserve issues for appeal in an area where the law is still being written.

Confidential Informants and Undercover Officers

Surveillance cases frequently rely on confidential informants (CIs) and undercover officers, and informant tips often supply part of the probable cause for a warrant. Beyond the reliability analysis described above, the defense may litigate disclosure of an informant’s identity where it is material to the defense, expose motives such as leniency deals or payment that bear on credibility, and—in undercover operations—raise entrapment where the government induced conduct the defendant was not predisposed to commit. These are fact-intensive issues that reward careful investigation of the informant’s history and the government’s inducements.

State and Federal Investigations

Surveillance evidence appears in both state prosecutions and federal cases, and the two systems involve different statutes, procedures, and resources. Federal task forces often bring substantial technological capabilities to bear, particularly in conspiracy and large-scale investigations, where CSLI, wiretaps, and informants are common. We help clients understand the rules that apply in their forum—and how to challenge the evidence against them.

Related Practice Areas

Electronic surveillance evidence is common in many types of cases. Learn more about how we defend charges where this evidence frequently appears:

Contact a Tennessee Criminal Defense Attorney Today

If the case against you relies on electronic surveillance, the way that evidence was gathered may make all the difference. Contact our office today to schedule a confidential consultation and learn how we can examine the government’s methods, test the warrant, and protect your rights.

This page is provided for general informational purposes only and does not constitute legal advice. Reading this information does not create an attorney-client relationship. The law governing electronic surveillance is complex and changes frequently—several issues discussed here are actively being litigated and may be resolved or altered by new decisions—and its application depends on the facts of each case. Case citations are provided for general reference and should be independently verified against current authority. You should consult a licensed attorney about your specific situation.