Dever was appointed to fill a vacancy on the Appellate Court. He served two partial terms on the Appellate Court, eventually becoming its presiding judge. For his second term, he had been reelected with more than 98,000 votes. Dever was assigned the initial case against those involved in the Black Sox Scandal. The arraignment began in February 1921. In March 1921, Dever rejected the prosecution's motion to indefinitely postpone proceedings and set a prompt peremptory trial date. This resulted in Robert E. Crowe, the Cook County state's attorney, opting to instead administratively dismiss the charges (nolle prosequi) and opted instead to present the case to a grand jury again for new indictments, to buy more time to put together a case and gather evidence. The new trial instead landed before judge Hugo Friend. Mayoralty 1923 mayoral election In 1923, Democratic party boss George E. Brennan selected Dever as having the best chance of defeating the incumbent, Mayor William "Big Bill" Thompson. Dever ran on a reform platform and Thompson withdrew from the race, with Republicans instead nominating Arthur C. Lueder, who was easily defeated by Dever. Mayoral term Dever was sworn in on April 16, 1923. Transit Early into his mayoralty, Dever had begun making plans to improve the city's public transit, which he had previously made a central issue in his mayoral election campaign. A longtime advocate for municipal ownership (an issue which had been a hot-button topic in Chicago, particularly during the Chicago Traction Wars), Dever initiated negotiations to purchase Chicago Surface Lines and the Chicago Rapid Transit Company, making them city owned-and-operated services. Dever began also formulating plans for transit expansions and the construction of a subway. Prohibition and crime In the autumn of 1923, the focus of Dever's administration shifted. On September 7, 1923, a shootout occurred took place at a South Side cafe between two rival groups of rum runners, killing one man. A week later the same two groups had another shootout, killing two people. He saw these shootings as an alarm that the city's bootlegging situation had become an epidemic. Dever himself opposed Prohibition; he was a "wet" Democrat. However, he observed that bootleggers had been making under-the-table payments to public officials and law enforcement, thereby corrupting the government. Also, while he disagreed with the policy of Prohibition, it was his personal philosophy that disregard for one law could foster an erosion in