In the matter of the application of the United States of America for an order directing a provider of electronic communication service to disclose records to the government

This is a brief filed in the 3rd Circuit Court of Appeals opposing an application for historical cell site location data on less than a showing of probable cause. CDT filed this "friend of the court" brief with the ACLU and EFF  in this case.  There is great concern about the practice of some federal prosecutors seeking court orders to track a person's location using cell phone tower registration data without  showing probable cause.  Because these orders are usually not made public — filed "under seal"–they are essentially secret.