I'm all for going after the bad guys but sometimes law enforcement agencies don't make themselves likable, especially when they can force someone to comply with what they want.
Are there other cases where subpoenas have been issued for tools that enable the gathering of evidence? Has that sort of thing always required a warrant?
Is it moot that a warrant was eventually issued? Or was the warrant only issued punitively because Lavabit didn't comply with the subpoena without regard to the validity of the subpoena in the first place?
"You can't throw the ball like that. Hand ball! 87 just knocked 12 over. Red card, red card! This ref is an idiot; he doesn't know any of the rules!"
They're not asking for evidence, they order the operator of the service to be complicit in aiding the government in impersonating the service towards all of its users.
There's a comment by "Jessica Darko" on the linked-to blog that I think warrants addressing. There is a big difference between a "search" for the purposes of the 4th amendment and a subpoena of a third party. Say the government is investigating Bob for tax fraud. It's a "search" subject to 4th amendment protections for the government to break into Bob's house and go through his drawers. It's not a "search" for the government to subpoena his accountant for any relevant financial records. It's a "search" for the government to break into the accountant's office to get those records, but the accountant can't hold up the 4th amendment as a shield against turning over those records pursuant to a court order.