I recently read a wired article about Silk Road and the arrest of Ross Ulbricht. The article describes how an FBI agent attempted to discover the true IP address of the Silk Road Server:
Tarbell [New York FBI] threw data at Silk Road, hoping to see the leak. He entered usernames with bad passwords (and vice versa) and pasted data into input fields—all the while using regular old freeware to analyze network traffic and collect the IPs communicating with his machine.
For the sake of discussion, lets assume that the actions above are violations of the CFAA. Under what circumstances is Law Enforcement allowed to attempt unauthorized access or exceed authorized access of a system as prohibited by the CFAA or laws. Does Law Enforcement need a warrant, probable cause, etc?