"A Jury of Her Peers" suggests that the male-run criminal justice system of the early twentieth century might have failed to deliver justice to women, not understanding the reality of their lives.
In this story, the men who arrive at the Wright farm to investigate John Wright's murder show no ability to empathize with a woman's existence. They ridicule the details of a farm woman's life as trivial. They dismiss Minnie's messy kitchen as a sign that she was a poor housekeeper, not as evidence of her deep emotional distress.
Only the two women, Mrs. Hale and Mrs. Peters, who are left alone in the kitchen while the men investigate elsewhere, are able to piece together the facts of the case, because only they understand what Minnie's life must have been like. They realize that after years of abuse and isolation, Minnie must have snapped after her husband killed her beloved canary. They implicitly recognize that, after suffering years of abuse, Minnie killed her husband as a way of trying to reclaim her own life.
Through showing how the male authorities belittle women's lives and women themselves, Glaspell raises concerns about a criminal justice system that puts men in charge of a woman's fate. Although Mrs. Hale and Mrs. Peters illegally suppress evidence in a murder case when they keep the dead canary from the men, Glaspell builds our sympathy and support for why they protect Minnie.