The team was established and recruited by the interplanetary conqueror Agamemno, who had set out to conquer Earth and its champions, the Justice League. By using his powers, Agamemno switched the villains' minds with those of the JLA, and although they were eventually forced out of their bodies, they had acquired everything they needed to know about their "counter-parts" inside and out. This consequently resulted in the JLA using the H-Dial to transform themselves into entirely different heroes. Then using his Power Ring through the Absorbascon, Green Lantern removed all knowledge of the JLA's secret identities from the Injustice Leagues' minds.
Some time later a coherent group formed under the title. This team was led by Major Disaster and consisted of: Big Sir, Cluemaster, Multi-Man, and Clock King. Largely ineffective, they often encountered the Justice League International and eventually somewhat reformed before then looking for a job from Maxwell Lord. This resulted in them becoming the core members of the short-lived Justice League Antarctica.
More recently, during Green Arrow and Black Canary's wedding, a wider and more extensive Injustice League was formed by Lex Luthor, Joker and Cheetah, who plan to rebuild America in which crime and corruption are accepted as part of the normal life. However to ensure that their plan will succeed, they need to destroy the Justice League of America.
In Season 8, Episode 21, "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, enabling numerous Metahumans to escape and begin her recruitment to form a team of Earth heroes.
In Season 1, Episode 14, "Revelation", the Injustice League reveals itself, consisting of: Atomic Skull, Black Adam, Count Vertigo, Joker, Poison Ivy, and Wotan. The creating plant creatures which attacked across the globe and they were ultimately defeated by a team of young superheroes and the Justice League.