The Supreme Court just ruled in United States v. Jones that the placement of a GPS tracking device on an individuals automobile without a warrant is a violation of the 4th Amendment. The New York Times does a good job with an overview of the case here: Justices Say GPS Tracker Violated Privacy Rights.
I am quite pleased with the result, but I found the opinion itself to be particularly interesting. First is that while the Opinion of the Court was only joined by 5 of the 9 justices (Justices Scalia, Roberts, Kennedy, Thomas, and Sotomayor), the other 4 (Justices Alito, Ginsburg, Breyer, and Kagan) concurred in the judgement, but differed in reasoning. So the Judgement was decided unanimously, which I think is a positive sign for future privacy cases.
Specifically I think this section from Justice Sotomayor’s concussing opinion is worth reading (emphasis mine).
More fundamentally, it may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties. E.g., Smith, 442 U. S., at 742; United States v. Miller, 425 U. S. 435, 443 (1976). This approach is ill suited to the digital age, in which people reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks. People disclose the phone numbers that they dial or text to their cellu- lar providers; the URLs that they visit and the e-mail addresses with which they correspond to their Internet service providers; and the books, groceries, and medi- cations they purchase to online retailers. Perhaps, as JUSTICE ALITO notes, some people may find the “tradeoff” of privacy for convenience “worthwhile,” or come to acceptthis “diminution of privacy” as “inevitable,” post, at 10, and perhaps not. I for one doubt that people would accept without complaint the warrantless disclosure to the Government of a list of every Web site they had visited in the last week, or month, or year. But whatever the societal expectations, they can attain constitutionally protectedstatus only if our Fourth Amendment jurisprudence ceases to treat secrecy as a prerequisite for privacy. I would not assume that all information voluntarily disclosed to some member of the public for a limited purpose is, for that reason alone, disentitled to Fourth Amendment protection. See Smith, 442 U. S., at 749 (Marshall, J., dissenting) (“Privacy is not a discrete commodity, possessed absolutely or not at all. Those who disclose certain facts to a bank or phone company for a limited business purpose need not assume that this information will be released to other persons for other purposes”); see also Katz, 389 U. S., at 351-352 (“[W]hat [a person] seeks to preserve as private,even in an area accessible to the public, may be constitutionally protected”). This is quite a good thing in my opinion.
Obviously this is not the last time electronic information and privacy will be making its way to the Supreme Court, but I am hopeful based on the opinion of the Court that some of the Justices will look at the larger implications.
As a side note, I find it amusing that, as a self-declared originalist uses the Katz v. United States decision so prominently in the opinion as that case greatly expanded the reach of 4th Amendment protections, aruably beyond the original meaning.