No search warrant.
The U.S. Court of Appeals for the District of Columbia Circuit became the arena. The feds argued that extended, 24-hours-per-day surveillance without warrants was constitutional based on previous rulings about limited, point-to-point surveillance of public activities using radio-based tracking beepers. The ACLU and those fine, upstanding folks at the Electronic Frontier Foundation, said that was bullshit. A warrant was necessary to keep this from being abused.
Today, the ruling. The judge told the feds to put a sock in it, they need a warrant. You can find the ruling as a .PDF on the EFF site. Here's the nuts and bolts -- the judge ruled that the Supreme Court ruling the feds were relying on was beyond the scope of the trial. Specifically, length and scope of the operation. "It is one thing for a passerby to observe or even to follow someone during a single journey as he goes to the market or returns home from work. It is another thing entirely for that stranger to pick up the scent again the next day and the day after that, week in and week out, dogging his prey until he has identified all the places, people, amusements, and chores that make up that person's hitherto private routine."
And now, a word from Jennifer Granick, the Civil Liberties Director at the EFF. "The court correctly recognized the important differences between limited surveillance of public activities possible through visual surveillance or traditional 'bumper beepers,' and the sort of extended, invasive, pervasive, always-on tracking that GPS devices allow. This same logic applies in cases of cell phone tracking, and we hope that this decision will be followed by courts that are currently grappling with the question of whether the government must obtain a warrant before using your cell phone as a tracking device."
Score another one for liberty!