The Torah in Parashat Ahareh-Mot (Vayikra 18:19) commands that one may not have relations with a woman “Be’nidat Tum’atah” – when she is in a state of impurity due to menstruation. Once a woman becomes a Nidda (menstrual woman), she remains impure until she immerses in a Mikveh, and relations with her are thus forbidden until after the immersion. The Sefer Ha’hinuch explains the reason for this command as based upon Hashem’s concern to distance us from anything which could be harmful. He writes that beyond the spiritual harm that could be caused by having a relationship with a Nidda, this could also cause physical harm, and so the Torah forbade marital relations during the time the wife is a Nidda. On the level of Torah law, the status of Nidda extends for seven days from the time bleeding first occurred, and the woman can then immerse and become Tehora (pure) the night after the seventh day. The verse states in Parashat Mesora (Vayikra 15:19), “Shibat Yamim Tiheyeh Benidatah” – “She shall be in her state of impurity for seven days.” The Rabbis understood the word “Tiheyeh” (“shall be”) to mean that a woman remains a Nidda even after the bleeding ceased, and even beyond seven days, until she immerses in a Mikveh. Therefore, relations remain forbidden until after immersion. This immersion, according to Torah law, can be performed after the seventh day since the onset of bleeding, even if bleeding continued throughout the seven days, as long as it has ceased before the immersion. The accepted practice, however, is that a woman who becomes a Nidda does not immerse until after seven “clean days” – meaning, until after she goes through seven days without experiencing bleeding. The Gemara says that Jewish women accepted this stringency to avoid confusion between ordinary menstruation and bleeding which requires waiting a period of seven “clean days.” When the bleeding stops, the woman performs an internal inspection called “Hefsek Tahara” to ascertain the cessation of bleeding, whereupon the seven “clean days” begin. She then performs an inspection each morning and afternoon during the seven days, and if no blood is seen, she immerses the night after the seventh day. Any female that experiences menstrual bleeding becomes a Nidda, regardless of her age. Theoretically, if even an infant girl would experience such bleeding, she would attain the halachic status of Nidda until seven days have passed and she immerses. A Shifha Kena’anit (non-Jewish maidservant) likewise becomes a Nidda as a result of menstruation, as she has begun the process of becoming a Jew. On the level of Torah law, a non-Jewish woman does not attain the status of Nidda, but the Sages enacted that even a non-Jewish woman is considered a Nidda as a result of menstruation. Therefore, a man who cohabits with a non-Jewish woman is regarded to have violated the prohibition of relations with a Nidda (as well as other prohibitions, represented by the acrostic “Nashgaz”: “Nidda,” “Shifha,” “Goya,” “Zona”). As far as Torah law is concerned, a woman becomes a Nidda only if she bleeds with a “Hargasha” (“sensation”), feeling the flow of blood. If a woman did not feel any bleeding but saw a bloodstain, then, according to Torah law, she does not attain the status of Nidda. The Sages, however, enacted that the discovery of a stain indeed renders the woman a Nidda, depending on the stain’s color and size. Halacha forbids relations with one’s wife not only during the time when she is a Nidda, but also when the onset of bleeding is expected, based on the menstrual cycle (“Ona Ha’semucha Le’vestah”). In order to safeguard against violations of this prohibition, the Sages enacted “Harhakot” – certain measures intended to create some distance between a husband and wife during the time the woman is a Nidda. The husband and wife during this time may not even casually touch one another, or directly hand each other objects. The immersion after the seven “clean days” must be performed specif