[username]

They already have a front door. It's called "get a warrant".

[afar]

Why is getting a warrant not enough? Seems the level of access and cooperation is as much or greater than a key or backdoor.

Isn't it relatively speedy to get a warrant? In some cases just hours?

[bradleyjg]

Divulging a password, in some circumstances, has been found by some courts to be covered by the fifth amendment right against self incrimination.

https://en.m.wikipedia.org/wiki/Fifth_Amendment_to_the_Unite...

[rakoo]

Because you still need the user's willfull cooperation. It doesn't work if the user doesn't cooperate or if he's not supposed to be aware that he is being listened to, which is I believe the case in most terrorism cases.