Extreme Justice forms out of Captain Atom's issues with current Justice League chairperson Wonder Woman and her handling of the Judgment Day event. Atom forms his own League in order to be more proactive than the other teams, seeking out threats and eliminating them. Atom eschews sanction by the United Nations, seeing such endorsement as a hindrance to the other League's effectiveness.
The team operates out of Mount Thunder, and on one of their first missions stops a military coup by a general, preventing a nuclear holocaust. The next mission involved them trying to cure Ronnie Raymond of his leukemia, where the the treatment reawakens his firestorm powers at a uncontrollable level. Amazing Man eventually absorbs the excess energy from Ronnie, and Professor Stein cures him once he returns from space.
Captain Atom then leads the Extreme Justice team in an invasion of the country Bialya, following Queen Beatriz's rebuilding of the Extremists. They invade the country, destroying many cyborgs and manufacturing facilities throughout the country. Following this mission, Extreme Justice is disbanded along with the various other Justice Leagues.