The Lawfare Podcast Lawfare Daily: Chatting on Chatrie with Adam Unikowsky, Michael Dreeben, and Richard Salgado
May 5, 2026
Richard Salgado, former Google lawyer and Stanford lecturer who handled warrants and tech briefs. Michael Dreeben, former Deputy Solicitor General experienced in Supreme Court Fourth Amendment cases. Adam Unikowsky, attorney who argued Chatrie and geofence litigation. They unpack geofence warrants, how Google’s Sensor Vault and Location History work, debates over algorithmic queries as searches, and what the Court seemed focused on.
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How Geofence Warrants Work
- Geofence warrants ask companies to identify all devices in a defined place and time, returning anonymized movement data then de-anonymizing suspects.
- In Chatrie the police drew a 150m geofence for one hour, got 19 device traces, then narrowed to 9 and later 3, leading to conviction.
Reverse Search Warrants Are Different
- Geofence and other reverse-search warrants start without a target user and compel providers to search across many accounts for identifying information.
- Google developed a three-step process to reduce privacy harm by returning anonymized matches, narrowing suspects, then providing additional data on selected accounts.
Carpenter's Shadow Over Chatrie
- Carpenter limited the third-party doctrine for long-term cell-site location because the data is deeply revealing and cheaply acquired.
- Chatrie raises whether opt-in Location History (more precise, account-based) deserves similar or property-based protection.