Prior to ADP, agencies like FBI could actually access a lot of information from Apple, primarily because Apple stored keys alongside your data. Which meant even

Prior to ADP, agencies like FBI could actually access a lot of information from Apple, primarily because Apple stored keys alongside your data. Which meant even though iMessage content was encrypted (and therefore useless), they could still get a lot of information from a request to Apple -- and Apple hands over quite a lot. FBI had a document all about that in 2021. Also important to note, ADP is opt-in currently.