The Trial of Mary Dugan is a 1929 American pre-Code film starring Norma Shearer.

Mary Dugan, a Broadway showgirl, is charged with murder in the knifing death of her wealthy lover and goes on trial for her life. When her defense counsel appears to bungle his job, Mary's brother Jimmy, a newly licensed attorney, jumps into the case to defend his sister. Jimmy's courtroom style is unconventional, but he seems to be holding his own against the prosecuting attorney... until a surprise testimony changes the course of the trial.