Starfleet General Order 7 was a directive that forbade contact with the planet Talos IV. It specifically stated, "No vessel under any condition, emergency or otherwise, is to visit Talos IV."
General Order 7 was made part of Starfleet policy following the visit of the USS Enterprise to Talos IV in 2254.
In particular, the end of "The Cage" seems to hint that they made that rule after Pike left"
Pike: Wouldn't some form of trade...mutual cooperation..
The Keeper: Your race would learn our power of illusion, and destroy itself, too.
But when Michael Burnham realizes Spock is trying to go there in Discovery, she gets no warnings and has no hesitation about setting a course.
Was there no death penalty at that time?