<P> The character's regular appearances quickly defined him as the archenemy of the dynamic duo, Batman and Robin; he killed dozens of people, and even derailed a train . By issue #13, Kane's work on the syndicated Batman newspaper strip left him little time for the comic book; artist Dick Sprang assumed his duties, and editor Jack Schiff collaborated with Finger on stories . Around the same time, DC Comics found it easier to market its stories to children without the more mature pulp elements that had originated many superhero comics . During this period, the first changes in the Joker began to appear, portraying him more as a prankster than threat; when he kidnaps Robin, Batman pays the ransom by check, meaning that the Joker cannot cash it without being arrested . Comic book writer Mark Waid suggests that the 1942 story "The Joker Walks the Last Mile" was the beginning point for the character's transformation into a more goofy incarnation, a period that Grant Morrison considered lasted the following thirty years . </P> <P> The 1942 cover of Detective Comics #69, known as "Double Guns" (with the Joker emerging from a genie lamp, aiming two guns at Batman and Robin), is considered one of the greatest superhero comic covers of the Golden Age and is the only image of the character using traditional guns . Robinson said that other contemporary villains used guns, and the creative team wanted the Joker--as Batman's adversary--to be more resourceful . </P> <P> The Joker was one of the few popular villains continuing to appear regularly in Batman comics from the Golden Age into the Silver Age, as the series continued during the rise in popularity of mystery and romance comics . In 1951, Finger wrote an origin story for the Joker in Detective Comics #168, which introduced the characteristic of him formerly being the criminal Red Hood, and his disfigurement the result of a fall into a chemical vat . </P> <P> By 1954, the Comics Code Authority had been established in response to increasing public disapproval of comic book content . The backlash was inspired by Frederic Wertham, who hypothesized that mass media (especially comic books) was responsible for the rise in juvenile delinquency, violence and homosexuality, particularly in young males . Parents forbade their children from reading comic books, and there were several mass burnings . The Comics Code banned gore, innuendo and excessive violence, stripping Batman of his menace and transforming the Joker into a goofy, thieving trickster without his original homicidal tendencies . </P>

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