The Dan Slott series took a different approach to the metafiction angle, making use of a concept dating back to Lee and Kirby's early "Fantastic Four" – that the heroes of the Marvel Universe permit licensed comic-book adaptations of their adventures to be published. Since all comics published before 2001 bear the seal of the Comics Code Authority of America (a federal agency in the Marvel Universe), they are considered legal documents admissible as evidence in the superhuman law cases on which She-Hulk works.