Justifier Helmets, as used during the Final Crisis, are a blend between Apokoliptian technology and the Mad Hatter's mind control devices. Used to control Darkseid's militaristic forces in the legions of Apokolips. They are powered by the Anti-Life Equation; forcing the wearer to listen to the Equation and submit, turning them into Justifiers.
Having been forced to see one of his daughters fall prey to the Anti-Life Equation, Doctor Sivana deactivates all helmets. Allowing Lex Luthor the chance to seemingly kill Libra.
Following the Final Crisis, the Earth's forces spent resources in hunting down the Justifier helmets and destroying them.