What does it mean to "run a still" in chapter 9? Why would this be frowned upon, especially in the early 1930s?

In chapter 9, Cecil Jacobs tells the entire playground that Atticus "defended niggers," and Scout asks her father to explain what Cecil Jacobs meant. Scout tells her father, "He [Cecil Jacobs] made it sound like you were runnin' a still" (Lee, 77). A still is a type of contraption that distills liquor, which people built and used to make homemade moonshine during the Prohibition Era. The Prohibition Era lasted from 1920 to 1933, and people used to produce alcohol in highly wooded areas in the Deep South using stills. Running a still was considered a serious crime during the Prohibition Era, which is why Scout uses the appropriate metaphor to describe Cecil Jacobs's reaction to her father defending Tom Robinson. Cecil Jacobs and the other racist community members frown upon Atticus’s decision to defend a black man, which is similar to how people viewed illegal bootleggers running stills during the Prohibition Era.