25 C.F.R. § 111.2
Where an Indian woman was married to a white man prior to June 7, 1897, and was at the time of her marriage a recognized member of the tribe even though she left it after marriage and lived away from the reservation, the children of such a marriage should be enrolled-and, also in the case of an Indian woman married to a white man subsequent to the above date but who still maintains her affiliation with the tribe and she and her children are recognized members thereof; however, where an Indian woman by marriage with a white man after June 7, 1897, has, in effect, withdrawn from the tribe and is no longer identified with it, her children should not be enrolled. In case of doubt all the facts should be submitted to the Bureau of Indian Affairs, Washington, D.C., for a decision.
25 C.F.R. § 111.2