A trial is set to begin in a case challenging the three-drug combination for lethal injections in Tennessee.

The trial is slated to start Monday in Davidson County Chancery Court. It's still unclear whether the legal proceedings will delay one death row inmate's execution scheduled for Aug. 9.

In the lawsuit, attorneys for 33 death row inmates claim the drugs haven't been used yet in Tennessee but present a substantial risk of serious and severe pain and suffering and were used in botched executions in other states.

In a previous filing, Attorney General Herbert Slatery argued the U.S. Supreme Court and other federal appeals courts have rejected constitutional challenges to using midazolam as the first drug in a three-drug combination.

Tennessee last executed someone in 2009.

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