Because this is not a nation of laws at all.
In a nation of laws, would it be acceptable for spies to have secret talks with the so called "Justice" department and get the green light to torture people, in spite of the various laws against it? Would a nation of laws allow agreements like that? "Don't worry, we wont prosecute, you are working for us"
A nation of laws might, change those laws, and legalize its spies using torture. Then it would be on the up and up. However, this country isn't that, and well.... turns out not just on that one issue.
This just is not, and really never was, a nation of laws.