The Joker had sold some nuclear-tipped missiles to some Middle-Eastern baddie types, and disaster was only narrowly averted. Then the Joker was hauled away- not back to Arkham but by the Feds, who were royally pissed off and vowed that “not guilty by reason of insanity” wouldn’t cut it this time: he had f****d with National Security. And I seem to recall the Joker doing time in an uber-secure facility in Antartica? How did that turn out?
Wish I could tell you more, but I wasn’t reading Birds of Prey at the time. The Antarctic facility is ‘The Slab’ - most recently featured in the pages of the Outsiders, during a breakout there. The Joker, the last time I saw him, was free and messing with President Lex, again in the pages of the Outsiders.
I also recall a brief stint when the Joker had diplomatic status with the Middle Eastern nation of Qurac… which may tie in to your storyline.
I read that BoP storyline, but as far as I remember, they left off with the world not being destroyed and the Joker going to the Slab. He might’ve escaped in another book. He’s prone to that. I think that storyline was more than a year ago, which would put it before his appearance in Outsiders, so I guess he got out somehow.