Senior Most Male Member: - It is a presumption of Hindu law, that ordinarily the senior most male member is the Karta of the joint family.
Jandhayala Sreeamma v. Krishnavenamma AIR 1957 A.P.434
In the case of Hindu Joint Family a suit to set aside on alienation filed by the younger of the two brothers within three years of his attaining majority would be barred by limitation if the elder brother, who was the manager and an adult has failed to sue within three years of his attaining majority.
The senior most male member is Karta by virtue of the fact that he is senior most male member. He does not owe his position to agreement or consent of other coparceners. So long as he is alive, may be aged, infirm, or ailing, he will continue to be Karta. Even a leper may continue to be the Karta1. However, in cases of insanity or any other disqualifications, the next senior male member generally takes over the Kartaship. Once this is done the former will cease to be a karta.
So long as the father is alive, he is the karta. After his death it passes to the senior most male member, who may be the uncle, son, if coparcenery consists of uncles and nephews, or who may be the eldest brother, if coparcenery consists of brothers.