When teaching the class about law, Gilda (played by Adrienne Barbeau) matter-of-factly states Lizzie Borden was innocent because she was tried and found not guilty. Al Capone is mentioned in the same episode and was never found guilty in court of the crimes he's undoubtedly associated with (except tax evasion). Back to Lizzie,

1. She was the only other person in the house at the time
2. No signs of forced entry, nothing stolen, no one sighted coming or going
3. She told a neighbor the night before "an enemy" might try to kill her father
4. She unsuccessfully tried buying poison that morning
5. A neighbor reported the sound of a woman's laughter coming from the mother's bedroom at the time of the murder
6. Lizzie's story about being in the barn at the time of her father's murder was unlikely because of the heat and lack of footprints
7. Motive. She had bad relationships with her father and especially her stepmother
8. She sent people away after the discovery of the murders
9. Three days after the murders, she destroyed her dress by fire

They missed an opportunity to have a discussion about how criminals can escape justice and instead pretended that the courts are infallible.