Proper noun
Bat-embargo
(fandom slang) A prohibition against having the same fictional characters appearing in multiple DC Comics animated series in the decade of the 2000s, which caused Batman's allies and enemies save for Batman himself to be unavailable for the animated series Justice League (although Joker, Clayface and Firefly made appearances in this show) and Justice League Unlimited, and Robin to be unavailable for animated series other than Teen Titans.