Grand jury subpoena for Signal user data, Central District of California
There is still a huge hole: all the contact info is available anyway in the phone's address book. Assuming the common practice of syncing that address book to the cloud, the prosecutors just need to subpoena Google or Apple, and they get full Signal contact list of each person.I am amazed that Signal claims to be private while requiring all chat participants to expose their government-regulated phone number often tied to the legal identity.