Privacy? Oh, bother

Remember the Fourth Amendment? Oh, that old thing. We'll never miss it:

With so little left private, the Fourth Amendment is all but obsolete. Where police officers once needed a warrant to search your bookshelf for “Atlas Shrugged,” they can now simply ask Amazon.com if you bought it. Where police needed probable cause before seizing your day planner, they can now piece together your whereabouts from your purchases, cellphone data and car's GPS. Someday soon we'll realize that we've lost everything we once cherished as private. And as we grieve the loss of the Fourth Amendment, we'll be forced to look deep in our hearts—and at the little pieces of plastic dangling from our keychains — and ask ourselves if it was all worth it. R.I.P.

The authors, a U.S. Court of Appeals chief judge and his law clerk, blame all of us for the murder of the Fourth, most recently by our smartphones, which allow law enforcment, with our collective blessing, to monitor our real-time geographic location. And they have an interesting observation about the beginning of the erosion of our privacy:

It started with the supermarket loyalty programs. They seemed innocuous enough — you just scribble down your name, number and address in exchange for a plastic card and a discount on Oreos. The problem, at least constitutionally speaking, is that the Fourth Amendment protects only what we reasonably expect to keep private. One facet of this rule, known as the third party doctrine, is that we don't have reasonable expectations of privacy in things we've already revealed to other people or the public.

I know I've written before that the supermarket tracking is no big deal, but putting it in this kind of perspective makes a difference. And the more information we voluntarily give to more and more people, the weaker our "reasonable expectation" of privacy becomes. Consider that the next time you think it's no big deal to give Best Buy your ZIP code.