The state of Texas acted on insufficient evidence when it removed more than 450 children from a polygamist sect's compound outside of Eldorado while it investigates allegations of abuse, a state appeals court ruled.

The Third District Court of Appeals said the state failed to present any evidence that the children's physical health or safety were in danger, or that the need for protection was "urgent and required immediate removal of the children."

The ruling could derail one of the biggest child-custody cases in U.S. history. Acting on a distress call from an alleged 16-year-old girl, the Texas Department of Family and Protective Services took all 468 children from the Yearning for Zion ranch, a compound operated by the Fundamentalist Church of Jesus Christ of Latter-day Saints. The FLDS church is a break-off Mormon sect that still practices plural marriage.

The state's decisive action caused a media stir and prompted 38 FLDS mothers to take up legal action to get their children back.

The state justified its action by citing reports of widespread, church-sanctioned underage marriage and possible sexual abuse of minors. The department's lead investigator added that under the "pervasive belief system" of the FLDS, boys are groomed to be perpetrators of sexual abuse and girls are raised to be victims. Twenty females living at the ranch had allegedly become pregnant between ages 13 and 17, and five of the 20 are still minors.