prohibition or rule laid down in the sixth verse: for the sister of a married woman is near of kin to her husband; because she sustains a near affinity relation to him, and a near blood relation to her with whom he has cohabited.
2. A man sustains to his sister-in-law the same relation which he sustains to his brother's wife, whom he is expressly forbidden to marry, (v. 16;) and, therefore, by parity of reason, he is forbidden to marry his wife's sister.
3. As the law addresses women as well as men, when it expressly prohibits a man to marry his brother's wife, it virtually prohibits a woman to marry her sister's husband; and, therefore, if it is unlawful for this woman to marry this man, it must be unlawful for him to marry her.
4. A man is forbidden to marry his mother's sister; and the reason assigned for the prohibition is this: "She is thy mother's near kinswoman." (Ver. 13.) Observe, the law does not say she is thy, but thy mother's, near kinswoman.
A wife's sister is to her precisely the same, her near kinswoman: and, therefore, by parity of reason, her husband may not marry his sister-in-law; because he is expressly forbidden to marry his