"We don’t need a brand‑new “AI Fourth Amendment” to insist on warrants that fit the technology."

— Aditya Mohan, Founder, CEO & Philosopher-Scientist, Robometrics® Machines

Scene: August 22, 2009 — San Diego

Cruiser lights washed red and blue over a late‑summer night on Imperial Avenue. A Honda with expired tags ticked as it cooled beside the curb. On the passenger seat: a scuffed iPhone, a cracked corner spidering like dried salt. The booking room smelled of coffee and copier toner; the phone lay on a square of gray felt while an officer scrolled—messages, photos, geotags, a calendar studded with errands and names. In minutes, weeks of a life unspooled: a contact card with a gang moniker, a picture of a car, a face in the background that looked too familiar. The search felt like any other incident‑to‑arrest routine. But it was not pockets and paper. It was a glass key to the “privacies of life.”

A second thread, 2007 — South Boston

Across the continent and two years earlier, officers arrested Brima Wurie in a Dorchester Avenue lot. At the station, a flip phone on the evidence table lit up: my house. Police opened the call log, traced the number to an address, got a warrant for the apartment, and found drugs and a firearm. Two small cases, two ordinary phones, one large constitutional question.

From street to Supreme Court (2014)

The Court heard argument on April 29, 2014, and on June 25, 2014 issued a unanimous opinion consolidating Riley v. California and United States v. Wurie. Chief Justice John Roberts wrote for the Court: “Modern cell phones are not just another technological convenience. With all they contain and all they may reveal, they hold for many Americans ‘the privacies of life.’” And the command that follows is crystalline: “Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple—get a warrant.” The opinion recognized limited carve‑outs for exigency (e.g., imminent danger, hot pursuit) and suggested practical evidence‑preservation steps—powering down or using Faraday bags—while a warrant is obtained. In one stroke, the Court translated eighteenth‑century text to twenty‑first‑century glass.

Why It Matters in 2025

The rule: Absent an exigency, officers may not search the digital contents of a phone seized incident to arrest without a warrant that is particular about what may be examined (date ranges, apps, file types, and search protocols). Riley reframed phones as pocket computers qualitatively different from wallets or cigarette packs. Since then, cases like Jones (2012), Carpenter (2018), and Kyllo (2001) share a through‑line: the Fourth Amendment’s core principles adapt to new surveillance tools without waiting for Congress to reinvent the Bill of Rights.

“Old law, new code.” Riley also stands for something broader: existing legal frameworks are capable of governing new technologies. After the Supreme Court’s 2024 retreat from Chevron deference, courts—not agencies—sit squarely with the task of reading old words in light of new facts. That’s good news for AI governance: judges can use the Fourth Amendment, the Stored Communications Act (ECPA 1986), the Wiretap Act, and longstanding particularity and minimization doctrines as statutory hooks and constitutional guardrails to cabin digital searches. We don’t need a brand‑new “AI Fourth Amendment” to insist on warrants that fit the technology.

AI Link — Forensic AI, Device Triage, and the Warrant Wall

What changes with AI: Police labs increasingly use mobile‑forensic suites and AI‑assisted analytics to accelerate investigations. These tools:

• Ingest full‑disk images, encrypted backups, and app sandboxes;

• Classify images and videos (CSAM detection, weapons, gang signs), run OCR on screenshots, and perform speaker diarization and speech‑to‑text on videos and voice notes;

• Summarize long chat threads, cluster conversations, extract entities, and build social graphs from contacts, location trails, EXIF, and Bluetooth beacons;

• Use embedding search to surface “similar” photos or phrases and on‑device LLMs to generate narrative timelines or “key findings.”

Riley’s constraint: None of that bulk processing may lawfully occur before a judge authorizes the places to be searchedand the digital things to be seized. AI does not widen the doorway—the warrant does. Practically, that means:

1. Scope binds the model. If the warrant authorizes only photos between June 1–30, 2009 and messages in App X, the AI pipeline must be technically constrained to those slices—no peeking elsewhere “because the model already saw it.”

2. Minimization by design. Build two‑step filters (hash/blocklists, date/app partitions) that exclude out‑of‑scope data prior to model analysis; prefer on‑the‑fly queries over full‑device ingestion.

3. Audit trails. Maintain verifiable logs of what the AI accessed, when, and under which warrant clause; preserve model versions and prompts to meet discovery, Brady/Giglio, and Daubert scrutiny.

4. Cloud spillover. Riley’s concern with “cloud” content matters: if a phone’s apps index remote data, warrants should specify whether synced or server‑side content may be queried; otherwise, confine analysis to on‑device stores.

5. Exigency is narrow. Real “now‑or‑never” risks (kidnapping, active shooter) can justify an immediate, targeted look—not a general AI sweep. Secure the device (e.g., Faraday bag), then get judicial authorization.

Bottom line for modern U.S. law: Riley is the pocket‑computer translation of the Fourth Amendment. It affirms that constitutional text and existing statutes can govern today’s AI‑accelerated forensics—so long as the sovereign arrives with the oldest permission slip in American search law: a particularized warrant.