In re Kenneth D.

Opinion of the Court by Corrigan, J.

The federal Indian Child Welfare Act of 1978 (25 U.S.C. § 1901 et seq.; ICWA) and California implementing law require juvenile dependency courts and appropriate agencies to inquire into a child’s native heritage and to notify a relevant tribe if there exists “reason to know that an Indian child is involved . . . .” (25 U.S.C. § 1912(a); see Welf. & Inst. Code, §§ 224.2, 224.3, subd. (a).) The question here is, when the required initial inquiry was inadequate, may an appellate court consider postjudgment evidence to conclude the error was harmless? We hold that, absent exceptional circumstances, a reviewing court may not generally consider postjudgment evidence to conclude the error was harmless. The sufficiency of an ICWA inquiry must generally be determined by the juvenile court in the first instance. Because no exceptional circumstances exist here, the Court of Appeal’s consideration of previously unadmitted evidence on appeal was error. In In re Dezi C. (_______, 2024, S275578) ___ Cal.5th ___ (Dezi C.), also filed today, we address the appropriate standard of harmless error review where the inquiry into a child’s native heritage…