The Electronic Frontier Foundation had an interesting piece about two weeks ago that I just ran across. The Supreme Court of Massachusetts recently ruled that it is against their state constitution for the police to track a vehicle using GPS without court approval. The interesting thing here is that the crux of their rationale is that the scale of GPS is too great that it interferes with the owner’s “possessory interest”. To be honest, my understanding of the law is weak enough that I’m not sure what “possessory interest” means and why GPS violates it. However, older US Supreme Court cases from the ’70′s ruled that beepers were permissible by the police without owner permission. Basically because GPS is more powerful and more exactly, it is a bigger threat. New York has similarly ruled that as well.
All in all, the case only has jurisdiction in Massachusetts, but it might set a precedent that Federal courts could follow.