I appeared on the Dateline NBC True Crime Weekly Podcast to discuss geofencing and the Fourth Amendment. podcasts.apple.com/us/podcast/m...

Mysterious death of Mississippi Black teen. Doctor's ex-wife allegedly plots his murder. Plus, geofencing.

Podcast Episode · Dateline: True Crime Weekly · July 16 · 32m

podcasts.apple.com

As many know, @bjard.bsky.social and I have been drafting a Technology Law coursebook for a few years. We've used it to teach classes at three institutions, including Yale Law School, and others have used chapters in their techlaw classes. We're excited to share the current version more broadly!

Chapter 10 unpacks the Precautionary Approach, including bans (I finally got to write about AWS!), general critiques (@casssunstein.bsky.social), and variations (moratoriums, licensing regimes, burden-shifting, etc) (Sachs). It closes with a GenAI X-risk case study (@mtokson.bsky.social).

TL Chapter 10: The Precautionary Approach

Technology Law Chapter 10: The Precautionary Approach BJ Ard and Rebecca Crootof Last updated May 2026. Comments welcome! Cite as: BJ Ard & Rebecca Crootof, The Precautionary Approach, in Technology ...

docs.google.com

If Chatrie transformed Fourth Amendment law, then what is Fourth Amendment law now? In the second part of a trilogy of blog posts on the Chatrie case, I offer a potential answer. www.dorfonlaw.org/2026/07/what...

In the final essay of his 3-part series on Chatrie v US, @mtokson.bsky.social puts the case in larger context: SCOTUS has rejected calls to reconceptualize 4th Amendment rights in property terms and provided a firm constitutional basis for protecting privacy against new technological threats. 👇

Chatrie v US was the first major SCOTUS 4th Amendment privacy ruling in 8 years. As @mtokson.bsky.social explains on the blog in the 2nd of a 3-part series on the case, it also established a new--sensible and protective--test for determining when surveillance requires probable cause and a warrant. 👇

I break down the Supreme Court's landmark Chatrie case and what it means in a new blog post at Dorf on Law. www.dorfonlaw.org/2026/07/brea...

I break down the Supreme Court's landmark Chatrie case and what it means in a new blog post at Dorf on Law. www.dorfonlaw.org/2026/07/brea...

Don't overlook Chatrie v US, a landmark SCOTUS ruling that enhanced the constitutional privacy rights of mobile phone users (i.e., nearly everyone) and limited government's ability to evade privacy rights via the 3rd-party doctrine. @mtokson.bsky.social analyzes & praises the decision on the blog.👇

The Michigan Law Review's Book Review Issue is officially out in print! You can access it here: repository.law.umich.edu/mlr/ You can access my review here: repository.law.umich.edu/mlr/vol124/i...

The Michigan Law Review's Book Review Issue is officially out in print! You can access it here: repository.law.umich.edu/mlr/ You can access my review here: repository.law.umich.edu/mlr/vol124/i...

Update: They got both the facts and the law right.

Matthew Tokson@mtokson.bsky.social · 2mo ago

Dear Supreme Court clerk drafting the Chatrie opinion this month, there's still time to get the facts & law right! Facts: Chatrie did not voluntarily disclose his data. dorfonlaw.org/2024/07/the-... Law: Retrospective surveillance of protected data is a search. papers.ssrn.com/sol3/papers....

Professor @mtokson.bsky.social, an information privacy expert, was quoted in @theguardian.com about a U.S. Supreme Court ruling that law enforcement's smartphone location data warrants require privacy protections under the Fourth Amendment.

US supreme court rules geofence warrants require constitutional privacy protections

Law enforcement’s use of warrants sweeping smartphone location data requires privacy protections, court rules

theguardian.com

Kagan's opinion in Chatrie relies heavily on the concept of retrospective surveillance, and correctly determines that retrospective searches should take into account the entire time period of potential surveillance - just as I argue here: papers.ssrn.com/sol3/papers....

The Court sends Chatrie back to the lower court for it to determine whether the search was reasonable, "meaning that each of its steps was properly described with particularity and found to be supported by probable cause." This is the victory I hoped for. The Court got it right.

This is huge: The court holds that police conducted a "search" for purposes of the Fourth Amendment "when they gained access to Location History data."

Matthew Tokson@mtokson.bsky.social · last mo.

Chatrie is out and it looks like privacy won! More on this as I read it.

Chatrie is out and it looks like privacy won! More on this as I read it.

Yet again the Supreme Court did not release Chatrie, so there's still time to get it right.

Matthew Tokson@mtokson.bsky.social · 2mo ago

Dear Supreme Court clerk drafting the Chatrie opinion this month, there's still time to get the facts & law right! Facts: Chatrie did not voluntarily disclose his data. dorfonlaw.org/2024/07/the-... Law: Retrospective surveillance of protected data is a search. papers.ssrn.com/sol3/papers....

My new short essay, Artificial Intelligence and the Lessons of History, is up on SSRN. papers.ssrn.com/sol3/papers....

My new short essay, Artificial Intelligence and the Lessons of History, is up on SSRN. papers.ssrn.com/sol3/papers....

No Chatrie case today at the Supreme Court - so there's still time to get Chatrie right!

Matthew Tokson@mtokson.bsky.social · 2mo ago

Dear Supreme Court clerk drafting the Chatrie opinion this month, there's still time to get the facts & law right! Facts: Chatrie did not voluntarily disclose his data. dorfonlaw.org/2024/07/the-... Law: Retrospective surveillance of protected data is a search. papers.ssrn.com/sol3/papers....

The Michigan Law Review's annual book review issue is out, which includes @mtokson.bsky.social's review of my book, "The Digital Fourth Amendment." The review is called "Fourth Amendment Anti-Theory," and it is available here, w/ the 1st 4 pages below. repository.law.umich.edu/cgi/viewcont...

Forgot to post: Our article on Decentering Property in Fourth Amendment Law is out in final form in the UChicago Law Review! lawreview.uchicago.edu/print-archiv...

Forgot to post: Our article on Decentering Property in Fourth Amendment Law is out in final form in the UChicago Law Review! lawreview.uchicago.edu/print-archiv...

Dear Supreme Court clerk drafting the Chatrie opinion this month, there's still time to get the facts & law right! Facts: Chatrie did not voluntarily disclose his data. dorfonlaw.org/2024/07/the-... Law: Retrospective surveillance of protected data is a search. papers.ssrn.com/sol3/papers....

Dear Supreme Court clerk drafting the Chatrie opinion this month, there's still time to get the facts & law right! Facts: Chatrie did not voluntarily disclose his data. dorfonlaw.org/2024/07/the-... Law: Retrospective surveillance of protected data is a search. papers.ssrn.com/sol3/papers....

New to SSRN: My short essay on the lessons of history for AI policy. It examines several historical episodes where elites made grave errors involving new technologies and threats, sometimes due to excessive optimism and sometimes excessive skepticism. papers.ssrn.com/sol3/papers....

New to SSRN: My short essay on the lessons of history for AI policy. It examines several historical episodes where elites made grave errors involving new technologies and threats, sometimes due to excessive optimism and sometimes excessive skepticism. papers.ssrn.com/sol3/papers....

🚨Publication Day for Sidewalk Nation!🚨 Sidewalks connect us all, and they connect commerce, tech, tax, property, policing, homelessness, surveillance, free speech, socioeconomic equity, public health, climate resilience, and more. www.hup.harvard.edu/books/978067...

Sidewalk Nation — Harvard University Press

An illuminating ramble along the American sidewalk: routinely unnoticed, yet central to daily life, neighborhood vitality, and significant legal controversies.Public infrastructure is as essential to ...

hup.harvard.edu

Florida sues OpenAI on various grounds (products liability, negligence, unfair trade practices), calling its products deceptive and unsafe and blaming OpenAI for several murders and suicides. variety.com/wp-content/u...