Editing Yevamot (section)

==== Chezkat Issurim (Presumption of Prohibition) ====
Chazakah (presumption) is a Torah law that when a doubt arises, out of doubt one should follow the status that existed before the doubt arose. The source of this law is in the Torah's approach to a house in which tzaraat (leprosy) appeared, where the house is considered a leprous house only from the time when the signs of tzaraat were definitely present.

When a doubt arises, there is a dispute among the Rishonim in a case where there is doubt whether a certain woman is divorced, and consequently there is also doubt regarding her tzarah (rival wife) whether she is a tzarat ervah (a rival wife of a woman forbidden due to a relationship that constitutes ervah), and if so, just as the ervah is exempt from yibum, so too the second is exempt. Some hold that if a person divorced his first wife - who was forbidden due to ervah, and only afterward married her tzarah, we assume out of doubt that her tzarah is not an ervah - just as she was not an ervah before he married her. Others hold that since the ervah was married, we say she was also married afterwards - like the previous status which is the chazakah, and therefore out of doubt her tzarah is possibly considered an ervah.