United States v. Ellis
The federal decision holding that real-time cell-site-simulator location is a Fourth Amendment search, while denying suppression because an armed, unfolding emergency—and alternatively good faith and inevitable discovery—made exclusion unwarranted.
Executive Summary
After an Oakland police officer was shot on January 21, 2013, investigators sought Purvis Lamar Ellis, a known gang member believed connected to an attempted murder the previous day, present near the officer shooting, armed, and at large. Oakland police and the FBI deployed two cell-site simulators beginning in the early morning of January 22 to locate Ellis’s phone. Officers did not first obtain a probable-cause search warrant. They proceeded under emergency pen-register procedures and obtained a state-court order within the statutory forty-eight-hour period. The court held that Ellis had a reasonable expectation of privacy in his phone’s real-time location and that simulator use was a Fourth Amendment search. It nevertheless denied suppression. The immediate danger to officers and the public, serious recent violence, weapons, gang activity, and risk of flight created exigent circumstances. The court also concluded that officers acted in objectively reasonable reliance on then-existing electronic-surveillance procedures and that lawful investigative activity would inevitably have led to the evidence.
Key Holdings at a Glance
An Armed Manhunt Following Police Shootings
Oakland police believed Ellis was a gang member involved in an attempted murder at a bus stop on January 20. He was also believed to have been near the shooting of an Oakland police officer on the evening of January 21 and to possess firearms.
Investigators considered Ellis dangerous, mobile, and potentially able to flee. Oakland police first used a simulator, followed by FBI use of another simulator as the search continued. The equipment located Ellis’s cellphone with the assistance of a simulator augmentation device.
The broader operation involved a SWAT perimeter, searches of apartments, removal of occupants, and the recovery of firearms from Apartment 212. The record did not clearly establish whether Ellis was in his own residence or another person’s residence at the precise moment the simulator located the phone.
How the Cell-Site Simulators Functioned
A simulator transmits as though it were a cellular tower. Phones in the area identify the equipment as an attractive tower and send signaling information. When locating a known device, the simulator initially receives identifiers from multiple nearby phones, isolates the known target identifier, and then uses signaling information from that target to refine location.
The government maintained that the devices were configured to operate like pen registers and did not collect communications content. Ellis argued that the equipment was technically capable of intercepting content and that deployment risked collecting information from uninvolved devices.
| Technical Question | Ellis Record | Agency Documentation |
|---|---|---|
| How many devices? | Two simulators used by OPD and FBI | Identify equipment, agency, operator, and handoff |
| Target mode | Locate a known phone identifier | Record identifier source and device attribution |
| Precision | Real-time locating; asserted accuracy about two meters | Preserve error radius, maps, and raw returns |
| Non-target interaction | Multiple devices initially transmit identifiers | Document filtering, retention, and deletion |
| Content collection | Government asserted locating configuration | Preserve configuration proving content was disabled |
Why Real-Time Simulator Location Was a Search
The Ninth Circuit had not yet decided whether simulator use or real-time phone location was a search. The court drew on Riley v. California, district-court CSLI decisions, United States v. Lambis, and State v. Andrews.
Modern phones usually remain on or near their users. Their real-time location therefore acts as a close proxy for a person’s location and can disclose entry into homes and other private places. The court found an objectively reasonable expectation of privacy in that information.
Simulator-derived signals carried an additional layer of involuntariness. They were not ordinary provider records initiated by the user or disclosed by a third party. Police equipment caused phones to respond and obtained location directly.
Standing and the Uncertain Residence
Only Ellis’s phone was targeted, so the court held that he could challenge its location. Other defendants could not assert the Fourth Amendment rights of uninvolved phone users whose devices might have interacted with the simulators.
The record was unclear about the premises where Ellis’s phone was located. The court therefore did not decide whether he possessed a privacy or property interest in that residence. It did not need to: Ellis’s own privacy interest in the real-time location of his phone was sufficient.
Emergency Pen-Register and Stored-Records Process
The pen-register statute generally permits an order based on a government attorney’s certification that the information is relevant to an ongoing investigation. The Stored Communications Act permits certain non-content records on specific and articulable facts—a standard below probable cause.
Under 18 U.S.C. § 3125, emergency pen-register or trap-and-trace use may begin before an order when an officer reasonably determines that a covered emergency exists and judicial approval is obtained within forty-eight hours. Covered emergencies include immediate danger of death or serious bodily injury and specified organized-crime activity.
The state order here authorized pen-register and trap-and-trace functions and ongoing carrier location information. It did not include a probable-cause finding and was not a simulator search warrant.
Why Exigent Circumstances Applied
Sworn statements established an immediate risk to officers and the public. Investigators believed Ellis was connected to an attempted murder and the shooting of an officer on consecutive days, was a known gang member, possessed firearms, and remained at large.
The need to locate him was not based on generalized investigative convenience. Delay created concrete risks of renewed violence and escape. The scope and timing of the deployment remained connected to finding the armed target during the active response.
| Exigency Factor | Evidence in Ellis |
|---|---|
| Severity | Attempted murder and shooting of police officer |
| Immediacy | Events occurred on consecutive days; suspect at large |
| Weapons | Specific belief Ellis possessed firearms |
| Public risk | Danger to responding officers and community |
| Flight | Mobile target could escape while authorization was sought |
| Scope | Deployment directed to locating known target phone |
The FBI Deployment as a Continuation
Ellis argued that even if Oakland police initially faced an emergency, later FBI deployment required a warrant because time had passed and officers had secured the area. The court viewed the federal effort as a continuation of the same unfolding manhunt.
That conclusion is not a perpetual-emergency rule. Agencies should continually reassess whether danger remains immediate, whether the target and location are contained, whether a judge is available, and whether the operation has shifted from emergency response to evidence gathering.
Good-Faith Reliance
As an alternative to exigency, the court concluded that suppression would not serve the exclusionary rule’s deterrent purpose. Officers used statutory emergency procedures, obtained judicial approval within the prescribed time, and operated before controlling appellate authority clearly defined simulator use as a search.
This differs from claiming that novelty alone creates good faith. The court emphasized the actual reliance on existing process, the emergency record, and the state of the law in January 2013.
Inevitable Discovery
The court also found that lawful investigative activity would have led to the evidence independently. Unlike a purely hypothetical alternative invented after the fact, the broader operation included active surveillance, containment, interviews, apartment searches, and warrant processes.
Inevitable discovery remains a remedy doctrine, not advance authorization for an unlawful search. Agencies may not deploy first and assume later that ordinary police work would have reached the same result.
Communications Content and Title III
Ellis argued that the simulators may have intercepted communications in violation of Title III. The court focused on the configuration and purpose reflected in the record and did not find a basis for suppressing content.
Because simulator hardware can possess capabilities beyond basic location mode, agencies should preserve configuration records showing what functions were enabled, what signals were acquired, and that communications content was disabled unless separately authorized.
What Ellis Does—and Does Not—Establish
Ellis is a federal district-court decision, not binding nationwide. It predates Carpenter and evaluates a 2013 deployment under the legal environment and emergency procedures then available.
The case does not hold that simulator use is outside the Fourth Amendment, that a pen-register order ordinarily substitutes for a warrant, or that every violent felony creates exigency. It holds the opposite on the search question and excuses the warrant only because of the particular emergency and remedy analysis.
| Proposition | Status Under Ellis |
|---|---|
| Real-time simulator location is a Fourth Amendment search | Held |
| Search warrant is ordinarily required | Held, absent exception |
| Exigency justified this deployment | Held |
| Any armed suspect creates exigency | Not held |
| Pen-register procedure permanently authorizes simulator use | Not held |
| Suppression follows every simulator violation | No |
Practical Guidance for Agencies
Emergency Simulator Deployment Checklist
- Identify the immediate danger of death, serious injury, escape, or destruction of critical evidence.
- Record the specific facts known when deployment is authorized.
- Explain why obtaining a warrant first is impracticable.
- Verify current attribution of the target phone and identifier.
- Use the narrowest capability, geography, power, and duration necessary.
- Contact a prosecutor, supervisor, and available judge as soon as practicable.
- Prepare warrant materials concurrently rather than waiting for the emergency to end.
- Record every handoff and reassess whether the exigency continues.
- Stop when the threat, target location, or statutory emergency ends.
- Complete return, discovery, deletion, audit, and after-action review.
Simulator Warrant Checklist
- Identify the offense, target, number, provider, and device identifiers.
- Establish probable cause connecting the device and requested location evidence.
- Name and explain the simulator capability.
- Distinguish provider records from direct government device interaction.
- Specify geography, duration, precision, settings, and stopping events.
- Address homes and other sensitive locations.
- Describe non-target collection, minimization, retention, deletion, and access.
- State whether content interception is technically possible and confirm it will be disabled.
- Require operational logs and a return describing actual use.
- Request separate authority for entry, arrest, phone contents, or expanded surveillance.
Litigation and Discovery Checklist
- Reconstruct the emergency chronologically from the first violent event through deployment.
- Identify each agency, device, operator, authorization, and operational handoff.
- Separate statutory compliance from the constitutional warrant-exception analysis.
- Examine whether the threat remained immediate at each deployment stage.
- Preserve configurations, identifiers, raw returns, maps, accuracy, and non-target data.
- Determine whether content or service effects occurred.
- Evaluate standing as to the target phone and any premises separately.
- Identify the affirmative authority supporting claimed good-faith reliance.
- Require evidence of lawful processes actually underway for inevitable discovery.
- Apply current controlling law rather than freezing practice in the 2013 legal environment.
Frequently Asked Questions
What did United States v. Ellis hold?
The court held that simulator use to obtain Ellis’s phone’s real-time location was a Fourth Amendment search, but it denied suppression because exigent circumstances justified the deployment and alternative exclusion exceptions applied.
What created the emergency?
Investigators connected Ellis to an attempted murder and the recent shooting of an Oakland officer, believed he possessed firearms, and considered him a danger to officers and the public.
Did officers have a simulator warrant?
No. They used emergency pen-register procedures and later obtained a lower-standard state-court order, not a probable-cause simulator warrant.
Why was the simulator still a search?
The phone was a close proxy for Ellis’s physical location, and the government obtained precise real-time location directly through its own equipment.
Did the court approve pen-register orders for routine simulator use?
No. The court’s ruling rested on the emergency and alternative remedy doctrines. It treated a warrant as ordinarily required.
What was the good-faith basis?
Officers relied on then-existing statutory emergency procedures and prompt judicial process during a period without controlling appellate simulator precedent.
What did inevitable discovery add?
The court found that independent lawful investigative activities already underway would have led to the evidence.
Is Ellis current nationwide law?
No. It is a 2017 federal district-court decision assessing a 2013 operation. Agencies must apply current controlling circuit, state, statutory, and policy requirements.
Primary Authorities and Operational Guidance
Federal decision finding simulator use was a search but denying suppression based on exigency and alternative remedial doctrines.
Read United States v. Ellis
Decision suppressing evidence derived from warrantless simulator use that identified a phone inside an apartment.
Read United States v. Lambis
Federal emergency pen-register and trap-and-trace provision, including covered emergencies and the forty-eight-hour approval rule.
Read 18 U.S.C. § 3125
Federal policy generally requiring a probable-cause warrant and addressing emergency use, disclosure, data controls, and auditing.
Read the DOJ policy
Later Supreme Court decision treating extended historical CSLI acquisition as a Fourth Amendment search.
Read Carpenter
Final Assessment
United States v. Ellis is valuable because it separates three questions often collapsed in practice: whether a search occurred, whether the search was reasonable without a warrant, and whether exclusion follows. The answer was yes, yes on exceptional facts, and no.
The decision does not weaken the warrant rule. It illustrates the demanding factual record needed to justify emergency deployment and the importance of statutory process, prompt judicial review, narrow targeting, continuous reassessment, and independent lawful investigation.