An Ohio man who became the third U.S. death row inmate in seven decades to survive his own execution filed a new appeal for mercy Tuesday, arguing that Ohio’s lethal injection protocol constitutes cruel and unusual punishment because one of its drugs may not work properly.

Alva Campbell, a 69-year-old man sentenced to death in 1998 for killing 18-year-old Charles Dial in a robbery, had his execution halted about 25 minutes after it was scheduled to start, according to the Associated Press. The execution team, it turned out, couldn’t pinpoint a vein that they could use to inject Campbell with a dosage of lethal drugs.

In court documents filed before the execution, Campbell’s lawyers warned that this was a possibility, as Campbell has a history of chronic heart and lung problems that can make finding a vein tricky. In fact, the prison was so worried that Campbell’s lungs would give out and he would stop breathing, while lying on the execution gurney, that the team gave him a wedge pillow to help him stay calm and alive until they could execute him.

Campbell’s lawyers also cited Ohio’s bad track record when it came to successfully carrying out executions. Though the first failed execution in modern U.S. history took place in 1946, when Louisiana’s attempt to execute Willie Francis using the electric chair failed, the second was much more recent: In 2009, an Ohio execution team made 18 attempts over the course of two hours to find a vein to inject Romell Broom with lethal injection drugs. Then-Gov. Ted Strickland ultimately ordered them to give up. Broom remains on death row, locked in a court battle where he argues that trying to execute him a second time would be unconstitutional.

Campbell’s new appeal to the U.S. Court of Appeals for the Sixth Circuit Court, however, technically centers around a different issue: the use of midazolam, a sedative that’s meant to render an inmate unconscious.

Midazolam has been used in several recent botched executions, including in Ohio. In 2014, the state executed convicted killer and rapist Dennis McGuire, even though McGuire reportedly gasped, snorted, and snored minutes after he should have been knocked unconscious. A judge ended up declare Ohio’s lethal injection procedure unconstitutional, leading the state to halt executions for years.

As drug manufacturers and distributors become more and more reluctant to allow their wares to be used in executions, however, states are scrambling to find drugs they can use in lethal injections. That’s led midazolam’s popularity to skyrocket.

Evidence “from recent executions demonstrates the disturbing signs that prisoners remain sensate to severe pain, aware, and conscious following injection of 500 mg. of midazolam or more are ‘the rule,’ not ‘the exception,’” Campbell’s lawyers write in his latest appeal.