Massachusetts prohibits incest and polygamy and restricts marriage between couples under the age of 18.
The marriage laws are codified in M.G.L. Chapter 207 and they read as follows.
Incest
 Section 1. No man shall marry his mother, grandmother, daughter, granddaughter, sister, stepmother, grandfather’s wife, grandson’s wife, wife’s mother, wife’s grandmother, wife’s daughter, wife’s granddaughter, brother’s daughter, sister’s daughter, father’s sister or mother’s sister.
Section 2. No woman shall marry her father, grandfather, son, grandson, brother, stepfather, grandmother’s husband, daughter’s husband, granddaughter’s husband, husband’s grandfather, husband’s son, husband’s grandson, brother’s son, sister’s son, father’s brother or mother’s brother.
Polygamy
Section 4. A marriage contracted while either party thereto has a former wife or husband living…shall be void.
Minors
The marriage of a person under the age of eighteen is prohibited unless sanctioned by the county’s probate court pursuant to Section 25.
The minor must file a petition with the court and the minor’s parents or legal guardians must consent to the marriage. After a hearing the court can then issue an order permitting the union.
The punishment for violating M.G.L. Chapter 207 “Shall be punished by a fine of not more than one hundred dollars” according to Section 52 of the law.
If you have any questions about the law please contact me at justin@jrmccarthy.com.
So, if I’m understanding this correctly, according to the law, a man is not allowed to marry his mother-in-law and a woman isn’t allowed to marry her father-in-law.
However, the law doesn’t specify if the man has to be currently married to the wife for her mother to fall under the “wife’s mother” restriction in the law. Nor does it specify if the woman must currently be married to the husband for his father to be considered as the “husband’s father” under the law.
As you show, there’s already a specific law regarding polygamy, so then the law must be specifically speaking about a former in-law.
This would seem to suggest that, as in many states with similarly worded laws, once you marry someone then their parent will permanently be off-limits as a future marriage prospect.
Regardless of whether or not that was the intention of the law a disgruntled former husband or wife could bring legal action against a former spouse who married their parent after their divorce.
So, for example, a man of 40 years of age who married a woman of 30 and later divorced her, could not then marry her 50 year old mother without bringing the threat of possible legal action under the laws against incest.
This law’s wording also doesn’t seem to refer to same-sex marriages, which are legal in Massachusetts. So, according to the wording of the law, a grandfather can marry his grandson, a grandmother can marry her granddaughter, a father can marry his son, a mother can marry her daughter, an uncle can marry his nephew, an aunt can marry her niece, a man can marry his brother, and a woman can marry her sister all without violating Massachusetts’ law on incest.
Am I incorrect on my interpretation of the law in either or both of these points?