The St. Petersburg (FL) Times has a good story today by Jamal Thalji, Should authorities need a warrant to put a GPS tracking device on your car?.
I'm quoted towards the end:
Those conflicting rulings mean the U.S. Supreme Court will likely decide the issue.
The real issue is resources, said University of Miami law professor Michael Froomkin. When the courts first gave the government the right to remotely track suspects, no one thought they'd one day have the money or technology to do so constantly.
“There was an unstated assumption behind a great deal of Fourth Amendment jurisprudence in our history that says surveillance is expensive and therefore has natural limits,” he said. “That unstated assumption that people took for granted is no longer true.”
And therein, I think, lies the problem — we are working with doctrine that doesn't fit the new technical and economic realities.