To really blow your mind, there is an entire system of classified patents. Some technology is too important to publish but corporations still need to patent it. But when Lockheed wants to sue Boeing over infringement of a classified patent they need to go to a classified court were the patent can be litigated without anything being revealed publicly.
It isn't altogether different than the use of private judges for celebrity divorces. Divorce proceedings are a matter of public record, unless you agree to hire your own judge and then everything can remain out of the public eye. Technically, these are arbitrators but very often are recently retired judges who agree to abide the current law.