Madonna Filippa deceived her husband Rinaldo de' Pugliesi by sleeping with Lazzarino de' Guazzagliotri in the town of Prato

Filippa was told by the Podestà (Judge) of Prato that the law dictated death for adultery

"Every man and woman should be equal before the law, and laws must have the consent of those who are affected by them .  .  . when this law was made, no woman gave her consent to it, nor was any woman even so much as consulted.   It can therefore be described as a very bad law." (Le leggi deono esser comuni e fatte con consentimento de coloro a cui toccano .  .  . e oltre a questo, non che alcuna donna, quando fatta fu, ci prestasse consentitmento, ma niuna ce ne fu mai chiamata, per le quali cose meritamente malvagia si puo chiamare.)

Ken Pennington, “A Note to Decameron 6.7:  The Wit of Madonna Filippa,”  Speculum 52 (1977) 902-905