Mr. Justice was, in his teenage years, recruited into the First Line along with Blackjack, Flatiron, Knight Templar, Dr. Mime, Major Mercury, Morph, Oxbow, Vulcan, Reflex, Rapunzel, Pixie, Firefall, Eternal Brain, Positron, Katyusha, Walkabout, Frank and Yeti. He was at this time known as Kid Justice. The founding members of the First Line was Black Fox, Effigy, Nightingale, Liberty Girl and Yankee Clipper.
He was highly influenced by his brother during their partnership, and once when faced with a difficulty, he asked himself "what would Clipper do?" He had several times been saved by Nightingale and Yankee Clipper. He has also been cited by teammates as the living legacy of Yankee Clipper after Clipper's disappearing in Marvel: The Lost Generation #4.
He seemingly died battling a Skrull fleetship along with the rest of the First Line group.