Gathered by Agamemno, who used his powers to switch his eight members minds with that of eight members of the Justice League. Though they were eventually forced out of the bodies they got everything they needed and knew their "counter-parts" inside and out, so the heroes used the H-Dial to switch their identities.
Some time later a coherent group formed under the name, lead by Major Disaster and including Cluemaster, Multi-Man, Big Sir and Clock King. Largely ineffective, they often encountered the Justice League International and eventually reformed (somewhat) and looked for a job from Maxwell Lord. This lead to them becoming the core members of the short lived Justice League Antarctica.
More recently, at Green Arrow and Black Canary's wedding, a more expansive Injustice League was formed by Lex Luthor, Joker and the Cheetah, who have plans to rebuild America, in which crime and corruption are accepted as part of the normal life. But first they need to ensure the total destruction of the Justice League of America.
In Season 8 episode, "Injustice", a group of meteor freaks called the Injustice League were sent by Tess Mercer to hunt down Doomsday. When Mercer took over LuthorCorp, she shut down the Black Creek facility and many metahumans escaped. She began recruiting them to form a team of heroes of Earth.
In "Revelation", the Injustice League reveals itself, creating plant creatures which attacked across the world. They were defeated by the team. It's members were: Atomic Skull, Black Adam, Count Vertigo, Joker, Poison Ivy, Ultra-Humanite, and Wotan