An NSL often includes a prohibition against even telling a companies own counsel that the NSL was served and for many years the FBI didn’t tell people this was

An NSL often includes a prohibition against even telling a companies own counsel that the NSL was served and for many years the FBI didn’t tell people this was even possible to challenge (until a 2008 appellate court ruling). Even after that point, barely one in fifty thousand letters even get to the point of a court hearing. It’s de factor quite similar. In addition, the legal challenge usually happens AFTER the letter is complied with, which makes it moot. These letters can, and do, end up causing companies to fold (e.g. lavabit) if they refuse to comply. Like many other national security issues (such as FISA court rubber stamps) there are theoretical checks and balances that do not tend to do much checking or balancing in practice.