Luffy - Liberating Justice/Free Justice I'd say. More lenient and open handed. Very woolly but work somehow.
Zoro - Prevailing Justice maybe? Since he's aiming for a title and had that whole thing about never losing. So his justice would be all about being enforced no matter the hurdle.
Law - Surgical or Precise Justice perhaps. More technical and efficient.
Whitebeard - Fatherly Justice, or maybe Strong Justice. Like how he does with his crew.
Roger - Adventurous or Hearty Justice, he seems to be a rather emotional free spirited type. Like Luffy's.
Xebec - Maybe Kingly Justice since he wants to rule the world. Possibly My Justice like Garp. Very wild and self centered.
Ace - Fiery Justice, duh. Probably similar to Roger's but more strict due to WB's influence.
Katakuri - Indomitable Justice or maybe Sweet Justice. Not too sure but it would be fair imo.
Mihawk - All Seeing Justice, he's Hawk Eyes Mihawk after all. Or Vengeful Justice due to his whole thing of bearing a grudge.
Shanks - Divine Justice perhaps based on his CD heritage + Kamusari....probably more like Ace's with a lot of emphasis on fate and destiny ig.