Someone using TOR should know that exit nodes will know that you used TOR, but by design they are not supposed to be able to find out who you were talking to, or what you were talking about.
The general assumption back when Silk Road was created was that TOR itself was safe, and the most likely way to be discovered was for your personal machine to be compromised. This belief was only strengthened by the FBI's repeated failures to take down Silk Road.
Heck, this was still a widespread belief AFTER Silk Road was taken down! For example http://motherboard.vice.com/read/the-fbis-deep-web-raid-seiz... quotes a security researcher who came to the conclusion in late 2014 that the FBI was just scanning TOR, and TOR itself had not been compromised.
For a comparison to phones, the Supreme Court has held that a list of people you called is not protected, but the contents of your phone calls are. Similarly I think they should rule in this case that the fact you're using TOR is not protected, but the details of what you were doing on TOR is covered by the 4th amendment.
By design, if the three or six nodes that you used compare notes, they can tell who you were talking to. That seems roughly the same as breaking a key into 6 parts and giving it to 6 different parties. I think the government would be able to go to each party and ask for their part, then put them together. Therefore, there's no expectation of privacy.
What actually happened is the researchers found a way to bypass the middle guy and reconstruct the info just from the two ends. That's still just comparing notes, but from fewer people.
Yes, I know how it was broken. But the question is what the expectation should have been. And given that expectation, then whether they should have had a warrant.
In our surveillance society, the government's theory is that it should never need a warrant, because terrorism. I strongly oppose that theory. I'm OK with taking down Silk Road, but get the warrant first.
The general assumption back when Silk Road was created was that TOR itself was safe, and the most likely way to be discovered was for your personal machine to be compromised. This belief was only strengthened by the FBI's repeated failures to take down Silk Road.
Heck, this was still a widespread belief AFTER Silk Road was taken down! For example http://motherboard.vice.com/read/the-fbis-deep-web-raid-seiz... quotes a security researcher who came to the conclusion in late 2014 that the FBI was just scanning TOR, and TOR itself had not been compromised.
For a comparison to phones, the Supreme Court has held that a list of people you called is not protected, but the contents of your phone calls are. Similarly I think they should rule in this case that the fact you're using TOR is not protected, but the details of what you were doing on TOR is covered by the 4th amendment.