Great 4th Amendment case
U.S. v. Jones holds that attaching a GPS device to an auto constitutes a "search" within the meaning of the Fourth Amendment. 9-0, on the result. Scalia writes for the majority, The liberal wing concurs, with a rather confusing opinion, starting by denying this is a Fourth Amendment issue, and ending by agreeing that it is. I can see the reasoning (that the violation was not the attachment of the device, but its use to monitor) but the wording is a little hard to follow.