(Nick Ut | The Associated Press) This March 31, 2016, file photo shows Rusty and Summer Page, foster parents of Lexi, a then-6-year-old girl with Native American ancestry, who was removed from their home, outside the California Court of Appeal in downtown Los Angeles. Lexi ultimately was placed with her father's extended family in Utah. A federal law that gives preference to Native American families in child welfare proceedings involving Native children is facing a significant legal challenge.