The ACLU of Maryland, representing a group of Baltimore City activists, argued for the court to block the city police department from using the "AIR" pilot program.

The Aerial Investigative Research flew a plane over Baltimore for six months. The pilot program ended last fall. In February, the city's Board of Public Works officially nixed the program.

"The residents of Baltimore were being treated as enemy combatants by their own police department," David Rocah, a senior staff attorney with the ACLU of Maryland, said. "This was the equivalent of everyone in Baltimore being forced to wear a tracking device every time they left the house."

The 8-7 decision from the 15-judge court ruled the aerial surveillance violated citizens' Fourth Amendment rights.