Orin Kerr comments on oral arguments in United States v. Jones, the GPS case argued before the Supreme Court this morning:
1) My basic reaction was that the outcome was too close to call. The Justices gave both sides a very hard time, and few Justices tipped their hand. The Justices pushed Michael Dreeben (arguing for the United States) on the consequences of his argument: If the Government was right, they noted, then the government can install a GPS device on all the Justices’ cars and watch them, too, along with everybody else. They pushed Steve Leckar (arguing for Jones) on the difficulty of identifing a clear Fourth Amendment principle to distinguish visual surveillance from GPS surveillance. The votes were hard to count, but if you had to summarize a reaction of the Court as a whole, I would say that the Justices were looking to find a principle to regulate GPS surveillance but unconvinced (at least as of the argument) that there was a legal way to get there without opening up a Pandora’s Box of unsettling lots of long settled practices.
2) The Justice who most clearly showed his cards was Justice Scalia. Justice Scalia made clear that he would overrule Katz v. United States; make common law of trespass the test for what is a search; and say that the installation of the device was a search because it was a technical trespass.
Read more on The Volokh Conspiracy.