Captain Marvel's teenaged sidekick Captain Marvel, Jr. proved to be popular. Initial hearing Detective Comics tried and failed to both have Fawcett cease publication of Captain Marvel comics and have Republic Pictures withhold release of the Captain Marvel serial via a cease and desist in June 1941. When the action went unheeded, Detective and Superman, Inc. filed suit against Fawcett in September 1941, naming Republic as a co-defendant. The lawsuit between Detective and Fawcett proceeded for seven years before trial finally began in March 1948. By this time, Detective Comics and Superman, Inc. had merged to create one company called National Comics, which became the sole plaintiff in the case. National's argument was that Captain Marvel's main powers and characteristics (super-strength, super-speed, invulnerability, a skin-tight costume with a cape, and a news reporter alter ego) were derived directly from those of Superman. Fawcett's counterargument was that although the two characters were indeed similar, the similarity was not infringing. National presented as evidence a binder over 150 pages in length, featuring panels from their comics of Superman performing superheroic stunts juxtaposed with panels of Captain Marvel doing the same stunts in magazines published at a later date than the Superman example. Fawcett countered in two ways: by providing examples of Captain Marvel performing those feats at even earlier points of publication, or by providing examples of other heroic comics characters such as Popeye or Tarzan performing those feats in earlier published comic strips. Testimony from Fawcett employees and artists hired by Fawcett on a freelance basis offered differing positions on whether or not the Fawcett creative teams had been required to copy from Superman comics. The trial was decided in Fawcett's (Captain Marvel's) favor because of information Fawcett's lawyers had uncovered about Superman's copyright status. The defense lawyers provided evidence that National Comics and the McClure Syndicate failed to copyright several of their Superman newspaper comic strips, and the trial judge decided that National had abandoned its Superman copyright such that it was no longer valid. The trial judge did find, however, that Captain Marvel was an illegal copy of National's Superman. Appeal National appealed the decision in 1951 to the United States Court of Appeals for the Second Circuit, with Judge Learned Hand presiding. Judge Hand's ruling in National's favor reversed a part of the trial court's decision. National's Superman copyright was held valid but the McClure strip was not