(You may not know this but) law enforcement has the capability to hack into computers using software (malware for you privacy advocates) called a Network Investigative Technique, or NIT.
Several cases have recently come before federal judges arising from the use of NIT to track thousands of computers accessing one dark website which was apparently a child porn site through the TOR network and from unknown locations.
The TOR network scatters a search through numerous routers around the world, so that the target computer does not record the IP address of the user. To make a long story short, NIT can get into that network and get those IP addresses—in this Texas case, because the FBI had seized the target computer and tracked down multiple defendants across the country.
In the confluence of child porn and the dark web, it seems as if courts are struggling to get a grip on some constitutional issues.
Courts have, so far, been split on the legality of this hacking, and their various reasonings have been shown that the law in these case may never be settled until Congress figures out what to do in this area.
The two primary bones of contention in the various suppression motions have been pegged to a defendant’s expectation of privacy and to whether or not hacking by law enforcement constitutes a “search” under the Fourth Amendment.
Although the court did not grant the suppression motion under R. 41(b)(4), a recent Texas case held in the Western District of Texas, San Antonio Division, did find that the hacking constituted a “search” (U.S. v Torres, No 5:16-CR-286-DAE). I highly recommend reading this 18-page case as instructive in some of these esoteric law enforcement issues and actions.
On the same topic, a February 2016 state of Washington district court decision, under the same facts, said that the hacking was not a search, because a person in the Tor network had no expectation of privacy—even though privacy is the reason that a person would employ Tor (U.S. v Michaud (W. Dist. at Tacoma, Case No.3:14-cr-05351-RJB). The DOJ apparently agrees with this view (Shock!).
The judge in the Texas case noted that the issues were confused enough that legislation was needed to clarify them. Enough said.