For the length of this messy trial, all four St. Louis newspapers devoted extensive front page coverage to the battling socialites and their lawyers, including huge courtroom drawings. Part of the reason the couple was willing to air their dirty laundry in a public courtroom was that both wanted custody of their son, William III. The trial opened in February, 1909, and the crowds that flocked to the courthouse each day to witness the drama were treated to tales of violence, drunkeness, atheism and cruelty.

Lillian charged that her husband drank to excess, and kept company with other women. William countered that among other things, his wife had been seen drinking and smoking in public. A divorce was granted in large part based on the testimony of a servant who testified that she had found feminine hairs of various colors in William's bathroom while Mrs. Lemp was absent.

Two years later, William and Lillian were back in court again, battling over the custody agreement of their child, William III. At the new trial, the Lemp family coachman related that there had been a series of monkey and chicken fights at the Lemp brewery stables, and that young William III had witnessed live birds being fed to the monkeys. According to Lillian's testimony, if the butler moved too slowly, William would take his pistol out, and lay it on the tablecloth. The former Mrs. Lemp also cited Mr. Lemp's habit of slaughtering neighborhood cats, as among the reasons for denying her ex-husband access to their son. William responded that he did not kill cats for pleasure, only shooting those that disturbed this sleep. William finally reacted to all of the publicity by building a country home on the Meramec River to which he increasingly retreated, and in 1915 was married to Ellie Limberg, widowed daughter of the late St. Louis brewer Casper Koehler.