Guilty Until Proven Innocent.
Discord: Please… Let me go free Tia.. I'm reformed! Someone is blaming these crimes and accusations on ME! You KNOW I would NEVER hurt anypony!

Tia: ….. I do not believe that you've committed these crimes, but things have changed in Equestria.. I.. I am sorry Discord.. But you were there at the scene of the crime and no pony else was there… You are guilty until proven innocent, and must stay down here until then.. With what crimes were committed, we are at war because of what you did..

Discord: But I… I didn't do it…

Tia: I am sorry… Goodbye old friend..

(here's the story, Sombra came back to life, killed some ponies and made sure Dizzy was there to see them, and be in jail because Sombra wants to take over, but Discord is just as powerful as him, so he needs to get Discord out of the way, which started a war between the ponies of Equestria, which is what Sombra wanted. Now it's in the far future and they are still fighting to this day..)