When the FBI seizes your messages from Big Tech, you may not know it for years

Every year, Facebook, Google and other technology companies receive hundreds of thousands of orders from law enforcement agencies seeking data people stash online: private messages, photos, search histories, calendar items — a potentially rich trove for criminal investigators. Often, those requests are accompanied by secrecy orders, also known as nondisclosure or gag orders, that require the tech companies to keep their customers in the dark, potentially for years.