"Specifically, these businesses would be substantially harmed if their customers knew that they were furnishing information to the FBI. The stigma of working with the FBI would cause customers to cancel the companies' services and file civil actions to prevent further disclosure of subscriber information."
The text implies that the FBI is engaged in the collection of communications data with the cooperation of service providers, and without the consent of the companies' customers and without court supervision.
The ACLU article states that "the government doesn't want you to know whether your internet or phone company is cooperating with its dragnet surveillance program because you might get upset and file lawsuits asserting your constitutional rights. Would it be such a bad thing if a court were to consider the constitutionality of the most sweeping surveillance program ever enacted by Congress?"
full story here:
https://www.infosecisland.com/blogview/13720-FBI-Surveillance-If-We-Told-You-You-Might-Sue.html