That's the problem. I'm almost 100% sure that, if you explained an NSL to Jefferson, he'd say that it clearly wasn't constitutional. Washington too, very likely. Adams, though, might have gone either way.
The Supreme Court has been a treasonous organization since Wickard v Filburn (8 of 9 justices then of course appointed by Roosevelt)
NSLs are unconstitutional.
> The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.