"Mad" did not have instant success, but found its audience by the fourth issue, which quickly sold out. The issue featured the Wood-drawn "Superduperman", a parody of Superman and Captain Marvel, including the copyright infringement lawsuit that National Periodicals (now DC Comics) had recently brought against Fawcett Comics. National, the owners of Superman's copyright, threatened to file another lawsuit over the parody. EC and National shared the same lawyer, who advised Gaines to quit publishing parodies. While Gaines was weighing this advice, Kurtzman discovered a legal precedent that backed "Mad"s right to parody. Gaines hired the author of that precedent to write a brief substantiating EC's position, but the lawyer sided with National. Gaines consulted a third lawyer, who advised Gaines to ignore the threat and continue publishing parodies. National never filed suit. When Kurtzman parodied National's Batman character just four issues later, the spoof included six separate picket signs, posters and other notices proclaiming that "Batboy and Rubin" was a comedic imitation (e.g. "Not a spittoon, not a cartoon, not a harpoon, but a LAMPOON!")