The three remaining Nebraska tribes have filed lawsuits against manufacturers and distributors of opioid painkillers.
The Winnebago Tribe, Omaha Tribe and Santee Sioux Nation of Nebraska filed lawsuits Tuesday in U.S. District Court in Omaha.
The Ponca Tribe and Knox County filed a lawsuit April 25.
Their attorney, Dave Domina, has said the companies misled medical professionals and misrepresented the dangers and addictive risks of their drugs.
More than 400 cities and counties across the country have sued drugmakers and distributors for costs associated with the addiction crisis.
In March a U.S. Senate committee was told that Native Americans and Alaska Natives saw a five fold increase in overdose deaths between 1999 and 2015.