25 CFR § 23.103 - When does ICWA apply?
(a) ICWA includes requirements that apply whenever an Indian child is the subject of:
(1) A child-custody proceeding, including:
(i) An involuntary proceeding;
(iii) A proceeding involving status offenses if any part of the proceeding results in the need for out-of-home placement of the child, including a foster-care, preadoptive, or adoptive placement, or termination of parental rights.
(2) An emergency proceeding.
(b) ICWA does not apply to:
(1) A Tribal court proceeding;
(2) A proceeding regarding a criminal act that is not a status offense;
(4) A voluntary placement that either parent, both parents, or the Indian custodian has, of his or her or their free will, without a threat of removal by a State agency, chosen for the Indian child and that does not operate to prohibit the child's parent or Indian custodian from regaining custody of the child upon demand.
(c) If a proceeding listed in paragraph (a) of this section concerns a child who meets the statutory definition of “Indian child,” then ICWA will apply to that proceeding. In determining whether ICWA applies to a proceeding, the State court may not consider factors such as the participation of the parents or the Indian child in Tribal cultural, social, religious, or political activities, the relationship between the Indian child and his or her parents, whether the parent ever had custody of the child, or the Indian child's blood quantum.
(d) If ICWA applies at the commencement of a proceeding, it will not cease to apply simply because the child reaches age 18 during the pendency of the proceeding.