Kryptonian law

Kryptonian law is dictated by the Kryptonian Science Council. There are many laws on Krypton, most notably is the law forbidding the the construction of space ships and space travel itself. Jor-El violated this law and was removed from the council.

History of the law
Twenty years before Krypton's destruction, Jax-Ur, and the rest of his rogue scientists build space arks in an attempt to exile the council into space. Because of his treasonous actions, he is sent to the Phantom Zone, and within fifteen years, space travel, and the invention of space traveling vehicles are outlawed on Krypton.