Detective Comics v Bruns Publications is one of the defining historical moments of American comic books. In a judgment handed initially handed down on April 7, 1939, and affirmed on appeal on April 29, 1940 the court ruled that Victor Fox's Wonderman character in Wonder Comics infringed on DC's Superman copyrights. In a lesser-known but also important historical moment, DC Comics went on the offensive against Victor Fox again just three months after that appeal was decided, this time over Batman and Robin. In a decision finally filed in 1942, Judge John Bright of SDNY wrote, "A comparison of the cartoons of The Lynx with Blackie the Mystery Boy published by the defendant Fox Publications, Inc., in its magazine Mystery Men Comics, and distributed by the defendant Colonial News Company, Inc., with the cartoons of The Batman with Robin the Boy Wonder, published by the plaintiff in its magazines Detective Comics and The Batman, convinces me there has been a deliberate copying by the defendant of drawings and cartoons of the Batman and his companion Robin…" The two issues involved in the lawsuit, Mystery Men Comics #13 & #14 featuring the Lynx and Blackie the Mystery Boy, are up for auction in the 2022 December 1 Fox Comics Showcase Auction #40214 at Heritage Auctions.
Judge Bright went on to clarify the issues of each publisher's comic books in question as "The issues of Detective Comics of April, 1940 (on the newsstands March 6, 1940), of May, 1940 (on the newsstands April 5, 1940), of June and July, 1940 (on the stands respectively on May 3 and June 5, 1940); and in the spring issue of "The Batman" on the stands April 24, 1940. These publications were all duly copyrighted by the plaintiff. The infringing publications by the defendants were contained in the "Mystery Men Comics" August and September, 1940, issues."
This corresponds to Detective Comics #38-41 and Batman #1 from DC Comics and Mystery Men Comics #13 and #14 from Fox Feature Syndicate. While there's only a very general resemblance between Batman & Robin and Lynx & Blackie, there seems to be a focus on layouts and story sequences in the language of Judge Bright's decision. For example, a glance through the issues in question reveals a panel in Mystery Men Comics #13 that's similar to the cover of Batman #1, and a sequence in Mystery Men Comics #14 that's similar to a sequence near the end of the first Joker story in Batman #1, among other similarities between the issues cited. A pair of Fox Feature Syndicate comic books with vastly underappreciated historical significance, Mystery Men Comics #13 & #14 featuring the Lynx and Blackie the Mystery Boy, are up for auction in the 2022 December 1 Fox Comics Showcase Auction #40214 at Heritage Auctions. If you've never bid at Heritage Auctions before, you can get further information, you can check out their FAQ on the bidding process and related matters.