Adam Donner is a former Assistant District attorney of Starling City. He worked under Kate Spencer, the District attorney, and was Laurel Lance's ex-boss; he fired her for her drug addiction. He lost his job after being caught up in the hostage crisis at the courthouse, making it his fault.
Moira Queen's trial
Adam later took Laurel out to dinner and made romantic advances towards her, but she rebuffed him.
Adam then served as the lead prosecutor in the trial of Moira Queen. Before the trial began, he informed Laurel that he had a "trump card" that will turn the jury against Moira. While cross-examining Thea Queen, he suddenly collapsed in the courtroom, an unwitting victim of Cecil Adams' newest scheme to spread Vertigo throughout Starling City. He was then kidnapped by Adams,who forced him to beg, on a live TV broadcast, for another injection of Vertigo to ease his withdrawal symptoms. Later he was freed by The Arrow.
Subsequent investigations and dismissal
When Laurel looked into Maya Resik's death, Adam refused Laurel's request to investigate Sebastian Blood, saying it would jeopardize his career. After Laurel was arrested for possession of drugs, he told her that charges will not be filed, but fired her from the DA's office.
Adam later reinstated Laurel as an ADA to be prosecutor against Frank Bertinelli. This turned out to be a ruse to lure out Helena Bertinelli so the police could capture her. It backfired, resulting in a hostage crisis at the courthouse. Kate Spencer stated to Laurel that he did not have the authorization to rehire her, and that he lost his job as ADA, although Laurel was able to parlay her own knowledge of the trap and its disastrous consequences into still getting rehired herself.