Previous use of the three drugs resulted in botched executions in Arizona, Oklahoma and Ohio, including one that left the patient convulsing and struggling for more than 30 minutes.
Prisons have been searching for new drugs as inmates wait in limbo for their last meal and to be strapped to their death beds. But as Ohio prepares to reintroduce the death penalty after a two-year hiatus, critics are crying out for a more humane solution.
They say the drug midazolam could lead to executions "akin in level of pain and suffering to being buried alive, burning at the stake".
The aim of the new method is to make it more humane than the previous method, one that was used during the execution of Dennis McGuire.
McGuire, a convicted killer, "experienced true pain and suffering" on January 16, 2014, according to an anaesthesiologist in a sworn statement.
In the chamber known as the "death house", the 53-year-old told family members he loved them shortly after the drugs began coursing through his veins.
Minutes later his stomach began to swell up and he "struggled and gasped audibly for air", according to witness Lawrence Hummer.
"I was aghast. Over those 11 minutes or more he was fighting for breath, and I could see both of his fists were clenched the entire time," Hummer wrote in an account published by The Guardian.
"His gasps could be heard through the glass wall that separated us. Towards the end, the gasping faded into small puffs of his mouth. It was much like a fish lying along the shore puffing for that one gasp of air that would allow it to breathe. Time dragged on and I was helpless to do anything, sitting helplessly by as he struggled for breath. I desperately wanted out of that room."
Anaesthesiologist Dr Kent Diveley said in a three-page statement following McGuire's death that neither of the drugs he was administered - midazolam and hydromorphone - could be depended on "to produce a rapid loss of consciousness" in their current doses.
Ohio will use the same drug, midazolam, but increase the dosage from 100 milligrams to 500 milligrams, more than 25 times the dose used to sedate patients in hospitals.
AKIN TO BURNING ON THE STAKE
Federal public defenders filed documents with the US Supreme Court on Wednesday declaring the use of the drug midazolam would lead to painful, lengthy executions.
"Such an execution would be inhuman and barbarous, akin in its level of pain and suffering to being buried alive, burning at the stake, and other primitive methods long since abandoned by civilised society," the filing said.
The lawyers said the new procedures are unconstitutional and executions in Ohio should be put on hold. The state will respond with its own filing.
Midazolam has a controversial history. People Magazine reported it was used without success to sedate Michael Jackson in the hours before he overdosed on propofol, another drug used to render a patient unconscious.
Stephanie Mencimer wrote in 2015 about her experience on the drug. She reported that the drug doesn't "put you in a coma-like state where you're impervious to pain" but it worked for her during a minor surgery.
"When I woke up, I remembered nothing, and my head was clear. But I couldn't help wondering if that pleasant sleep I'd just had would have been so pleasant if it had been followed by an injection of (the drug) which states use to paralyse an inmate and suffocate him."
Ronald Phillips will be wondering the same thing. During a previous attempt to postpone his execution, he said he had a lifelong fear of needles that made his veins shrink.
When prison doctors gave him a check-up prior Ohio halting executions, they couldn't find a vein.
He told The Associated Press: "I guess the Lord hid my veins from them". He'll be praying the same thing happens on January 12.
