Baltimore police have been running an aerial surveillance program capable of tracking people and cars since early 2016, which is being paid for not by the city but an unnamed private citizen, and without public input.

Bloomberg Businessweek said the surveillance has been conducted since January by a camera-equipped Cessna that circles the city recording what is going on below. The police use the imagery to solve crimes and track down criminals.

However, the fact the public was not fully informed of the program is problematical to the ACLU.

“It continues to be stunning that American police forces feel that they can use deeply radical and controversial surveillance systems, which raise the most profound questions about our society and its values, without telling the public that will be subject to these technologies—the public they are supposed to be serving,” Jay Stanley, senior policy analyst for the ACLU, wrote in a blog post.