Is the father or mother-in-law's brother mahram?
Well, first you need to understand what the term
mehram means. It means the person with whom marriage is not allowed. We people now a days confuse our selves by thinking that the
mehram means the person who we can chat out with. I have heard some fellow saying this which I never knew at that time that it is wrong. I will try to be using simple english instead.
Father is someone, who is male and is involved in our birth. Which means there is a relation of us with him by blood. So we cannot marry him, which means that he cannot be married to the person having a blood-relation with, making him a
mehram for his daughters.
Do you have a relation with him? No. How? Have a look below.
You married someone, whose mother's brother has no relation directly to the person who you married. If you meant to say Mother-in-law then she was a
mehram for you, since she is having a blood-relation to the spouse. But other relations are not
You need to consider some other points too, such as if mother-in-law's brother was fed milk by the same female by whom you were fed, then you're having a
mehram relation to him too.
In-law mahrams with whom one becomes mahram by marrying someone: father-in-law, mother-in-law; son-in-law, daughter-in-law, stepfather (mother's husband) if their marriage is consummated, stepmother (father's wife) if their marriage is consummated; stepson (husband's son) if their marriage is consummated, stepdaughter (wife's daughter) if their marriage is consummated;
Mother in law's sister is not mahram by assumptions and opinion of the scholars. And father in law's brother is not mahram similarly. My opinion is that brother and sisters of mahram are also mahram since they are directly blood related. There are no direct and literal evidence from Quran or sunnah that they are non mahram. For example, Quran mentions wet nurse as mother and her daughters as mahram but we know from hadith that wet nurse's brother is also mahram. This establishes the fact that a single mahram relation creates a full tree of mahram relation as they all are blood related.
Of course they are mahrams! And this is stated in the Quran, Surat An-Nisā' 4:23:
Prohibited to you [for marriage] are your mothers, your daughters, your sisters, your father's sisters, your mother's sisters, your brother's daughters, your sister's daughters, your [milk] mothers who nursed you, your sisters through nursing, your wives' mothers, and your step-daughters under your guardianship [born] of your wives unto whom you have gone in. But if you have not gone in unto them, there is no sin upon you. And [also prohibited are] the wives of your sons who are from your [own] loins, and that you take [in marriage] two sisters simultaneously, except for what has already occurred. Indeed, Allah is ever Forgiving and Merciful.