Digital Evidence and the Fourth Amendment's Evolution
Carpenter v. United States (2018) was a watershed moment for digital evidence law. Chief Justice Roberts' majority opinion acknowledged what lower courts had been reluctantly holding: that the third-party doctrine developed in the analog era doesn't translate cleanly to the digital age. The detailed, comprehensive picture of a person's movements revealed by historical CSLI "achieves near perfect surveillance, as if it had attached an ankle monitor to the phone's user."
Carpenter didn't resolve every digital evidence question — it explicitly left open how far its reasoning extends. The result is ongoing litigation across the circuits that is rapidly developing the law governing government access to digital evidence. For defense attorneys, this means both opportunity and complexity.
Cell Site Location Information (CSLI)
Carpenter squarely holds that government access to historical CSLI records (seven days or more) requires a warrant. The open questions concern real-time CSLI, shorter historical periods, and whether Carpenter's reasoning extends beyond CSLI.
Post-Carpenter, most circuits have held that real-time CSLI also requires a warrant — the rationale for treating historical and real-time CSLI differently is unclear under Carpenter's logic. The strongest suppression arguments focus on:
- Whether the warrant affidavit established probable cause specifically connecting the defendant to the phone number whose CSLI was obtained
- Whether the temporal scope of the CSLI request was overbroad relative to the alleged criminal activity
- Whether the geographic scope was appropriately limited
Geofence Warrants
Geofence warrants — orders directing Google or other providers to disclose the identity and location data of all devices within a geographic area during a specified time — have generated significant Fourth Amendment litigation. The circuits are split on their constitutionality, with some courts finding them categorically overbroad and others allowing them with appropriate limitations.
The strongest suppression arguments against geofence warrants focus on particularity — the Fourth Amendment requires that warrants particularly describe the place to be searched and the things to be seized. A warrant requesting all devices within a geographic area does not particularly identify the suspect, raising serious overbreadth concerns. Suppression arguments in geofence cases should also analyze whether the probable cause showing was adequate to justify the scope of the search.
Cloud Storage and Email
The Stored Communications Act (SCA) provides some statutory protections for stored electronic communications, but its framework — written in 1986 — doesn't map cleanly onto modern cloud services. Courts have increasingly held that the constitutional protections of the Fourth Amendment require warrant access to content stored in cloud services.
Practically: government access to the contents of email or cloud storage files without a warrant is increasingly vulnerable to suppression challenge. Focus the challenge on: (1) whether a warrant was obtained; (2) if so, whether the warrant particularly described the accounts or communications to be searched; (3) whether the executing agents stayed within the warrant's scope.
Device Searches Incident to Arrest
Riley v. California (2014) held that the search-incident-to-arrest exception does not permit warrantless cell phone searches. Riley is well-established but continues to generate litigation at the edges: when is a device "searched" as opposed to merely observed? Does a brief examination of an unlocked screen constitute a Fourth Amendment search? Can an officer compel a suspect to provide a biometric unlock (fingerprint or face ID)?
The biometric unlock question is being actively litigated, with courts reaching different conclusions about whether compelling biometric authentication is testimonial (and thus Fifth Amendment-protected) or merely physical. Current circuit splits on this issue create suppression opportunities where the government compelled biometric access without a warrant.
Building the Digital Evidence Suppression Record
Effective digital evidence suppression practice requires careful attention to the record. Obtain all documentation of the government's data acquisition: warrant applications, orders, returns, and any relevant provider communications. Analyze whether the legal process used matches the type of data obtained. Identify every step where the government acquired data without appropriate legal authority.
AI case analytics are particularly valuable here for identifying factually similar suppression decisions — cases where courts have addressed the same type of data acquisition under similar circumstances — to support the argument that the acquisition here violated the Fourth Amendment.