wtf is a 'pen register'?
"A pen register is an electronic device that records all numbers called from a particular telephone line. The term has come to include any device or program that performs similar functions to an original pen register, including programs monitoring Internet communications."
http://en.wikipedia.org/wiki/Pen_registerBasically they monitored all the internet usage of Ulbricht for a few days, this was "judicially authorized".
"The Pen Registers did not collect the contents of any communications. They collected only routing information, such as the IP addresses being contacted using the account, router, and devices, the ports being accessed, and the MAC addresses of the devices involved.
We used the Pen Registers to track when Ulbricht was connected to the Internet and what IP addresses and ports he was connecting to. By monitoring when Ulbricht appeared to be online, and comparing it to the times when DPR appeared to be logged in to Silk Road (as reflected by his activity on the Silk Road discussion forum), additional evidence was collected corroborating that Ulbricht was in fact DPR.
More at 18 - 21 in the declaration
I am not 100% sure it was actually judicially authorized as the defense had challenged the use of the pen register as unconstitutional because the government did not get a warrant.
I would not at all be surprised if this case made it's way to the supreme court because of the super high stakes for Ross. Not only is he facing basically life in prison, but he is disincentived to accept a guilty plea because if he does he would likely end up not being able to find a job (despite likely being a very smart kid) and likely having to give up what is essentially $70+ million dollars at current exchange rates. The defense has made some long-shot motions in the case, and have been ruled against pretty much all the time, but it does bring up some good points that have essentially been ignored.