Grand jury subpoena for Signal user data, Central District of California

27 Apr 2021

It’s the first half of 2021 – nearly five years since the “first half of 2016” – but in many ways not much has changed. The United Kingdom is still trying to figure out Brexit, another Justin Bieber song hit #1 on the charts (is it too late now to say sorry?), and Signal still doesn’t really know anything about you.

So when we received this subpoena from the United States Attorney’s Office in the Central District of California, it felt like 2016 all over again. Nostalgia can be great, and just like last time we got in touch with the ACLU to work with them on our response.

Because everything in Signal is end-to-end encrypted by default, the broad set of personal information that is typically easy to retrieve in other apps simply doesn’t exist on Signal’s servers. The subpoena requested a wide variety of information that fell into this nonexistent category, including the addresses of the users, their correspondence, and the name associated with each account.

Just like last time, we couldn’t provide any of that. It’s impossible to turn over data that we never had access to in the first place. Signal doesn’t have access to your messages; your chat list; your groups; your contacts; your stickers; your profile name or avatar; or even the GIFs you search for. As a result, our response to the subpoena will look familiar. It’s the same set of “Account and Subscriber Information” that we provided in 2016: Unix timestamps for when each account was created and the date that each account last connected to the Signal service.

That’s it.

Savvy readers of the documents below will notice something new: the “Information Sufficient to Show Interstate Wiring” segment in the subpoena and response, which appears to be intended to support a jurisdictional theory that Signal messages cross state lines, even when they are sent between users in the same state. These questions weren’t in the subpoena from 2016, and they feel like something out of a Law and Order episode from the mid-90’s when “The Internet” was still young and people didn’t really understand how it worked.

If you live in the United States and your friend in Montreal takes a picture of the downtown skyline outside of their window and sends it to you over “The Internet,” have you just visited Canada? Is your friend now an “international” photographer whose work is so powerful it transcends borders? These are questions for a good lawyer, we suppose.

Speaking of good lawyers, we’d like to thank the ACLU for their assistance – particularly our counsel for this response, Brett Max Kaufman and Jennifer Granick.

We’d also like to thank everyone who uses Signal. Our commitment to you remains unchanged. We’ll keep working with effective and talented organizations like the ACLU to respond to future government requests, and we’ll keep publishing our responses here.

The transcript for this request can be found below.

The Subpoena

Our Response