In a brief supporting the government, the Center on the Administration of Criminal law argued that GPS technology enhances the government's ability to strategically increase its presence in communities, and to better allocate resources. The brief urges the Supreme Court to uphold the ability of law enforcement to use a "new means of technology to conduct non-intrusive surveillance of vehicles in public spaces."

The U.S. Court of Appeals for the District of Columbia last August , ruling that the government has no authority to conduct around-the-clock GPS surveillance of suspects without a warrant.

"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," Judge Douglas Ginsburg wrote for the three-judge panel that reviewed the case.

"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," Ginsburg added.

Such tracking yields information that would not have been available to the government via other methods of surveillance. the appeals court held.