In 1879 La Flesche acted as the chief's interpreter during his trial at Fort Omaha, Nebraska. She also testified as to conditions on the reservation in Indian Territory. Standing Bear successfully challenged the lack of grounds of his arrest and imprisonment, arguing before the United States District Court that Indians were persons under the law, and had all the rights of US citizens. Tibbles attended and reported the case, which gained national attention. "Standing Bear v. Crook" (1879) was a landmark civil rights case, with the judge deciding that Indians had certain rights as "persons" and citizens under the US constitution.