He said the ruling will be appealed to a federal appeals court and if that court also says ICWA is unconstitutional, “the chances are basically 100 percent" that the case will end up before the U.S. Supreme Court.

Fletcher, a member of the Grand Traverse Band of Ottawa and Chippewa Indians, said while the Supreme Court has heard cases related to ICWA in the past, it has so far refused to hear challenges to the entire law. He said he's not sure how the current court would rule on this case.

"If ICWA is struck down in whole or in part, the victims will be our children and our families, Native children and Native families," the leaders of the tribal defendants — the Morongo Band of Mission Indians and the Cherokee, Oneida and Quinault nations — said of the ruling in a press release.

"Before ICWA, as many as one-third of all tribal children were forcibly removed from their families and their communities by state governments. Thorough and objective analysis of the systematic removal of Indian children from Indian homes found many removals were wholly unjustified. These policies devastated tribal communities and we refuse to go back to those darker days," the release said.