The lawsuit seeks a judge’s order to prevent the state from moving forward with executions until it enacts regulations that comply with state and federal laws, and provides an opportunity for adequate input and review.

The Nebraska Department of Correctional Services has defended its protocol, which gives Director Scott Frakes greater flexibility to choose which drugs are used in executions. The lawsuit takes issue with the department’s claims that its staff didn’t produce any early drafts of the protocol and didn’t consult with experts before approving the new version.

Nebraska previously relied on a protocol with three specific drugs, but abandoned it after repeatedly failing to get sodium thiopental from overseas suppliers. The drug is no longer manufactured in the United States.

“Nebraskans of goodwill hold different point on the death penalty,” said Danielle Conrad, executive director of the ACLU of Nebraska. “However, Nebraskans across the political spectrum agree that when the state seeks to implement its most grave function, it must do so within the bounds of the law.”

The lawsuit was filed in Lancaster County District Court on behalf of state Sen. Ernie Chambers, of Omaha, and the Rev. Stephen Griffith, who have both fought to abolish the death penalty.

Chambers also filed a formal complaint with the Legislature last week, alleging that Nebraska’s lethal injection protocol is unconstitutional. The complaint was referred to the Judiciary Committee for a possible hearing.

Nebraska corrections officials have taken several steps in the last year to resume executions after more than two decades. The last execution was in 1997.

The department recently notified death-row inmates Carey Dean Moore and Jose Sandoval of the drugs it intends to use in their executions, but the Nebraska Supreme Court hasn’t approved a death warrant for either man.

A Department of Correctional Services spokeswoman said the agency doesn’t comment on pending lawsuits.