OKLAHOMA CITY (AP) – Attorneys for several Oklahoma death row inmates are appealing to the U.S. Supreme Court to outlaw a sedative that is used in the process of lethal injection. The appeal is a result of a failed lethal injection one year earlier. The ruling could force several states to use alternative means in the process of lethal injection.

The drug under scrutiny is called midazolam. It is the first part of a first of three-drug combination. Clayton Lockett struggled in pain through a 43-minute execution on April 29, 2014 before Oklahoma prison officials had to stop the process.

Arizona, Florida, Ohio and Oklahoma are the four states that use midazolam in lethal injection. Louisiana, Alabama, and Virginia are three states that allow the use of midazolam but have never gone through an execution using the drug.

Obtaining execution drugs from pharmaceutical companies has been increasingly difficult for the states where lethal injection is legal. States have passed laws preventing important information about the drugs from the public.