What if a government spy agency had power to copy and data mine information about ordinary Americans from any government database? This could include records from law enforcement investigations, health information, employment history, travel and student records. Literally anything the government collects would be fair game, and the original agency in charge of protecting the privacy of those records would have little say over whether this happened, or what the spy agency did with the information afterward. What if that spy agency could add commercial information, anything it – or any other federal agency – could buy from the huge data aggregators that are monitoring our every move?
What if it wasn't just collection but also sharing? Anything that was reasonably believed to be necessary to "protect the safety or security of persons, property or organizations" or "protect against or prevent a crime or threat to national security" could be shared. Imagine the dissemination was essentially unlimited, not just to federal, state, local or foreign governments but also to individuals or entities that are not part of the government.
It has already happened.