Series cast members Rose Byrne and Tate Donovan, portraying Ellen Parsons and Tom Shayes respectively, secured their parts through auditions. Byrne had been unavailable when she was initially approached because she was shooting the film "28 Weeks Later" but auditioned later when the part had not yet been cast. Both Byrne and Donovan prepared for their roles by consulting lawyers and attending court trials. According to producers, the characters of Ellen's fiancé David Connor and his sister Katie were the hardest to cast.