JEFFERSON CITY - The drug famous for killing Michael Jackson is at the heart of a debate concerning the execution dates of 27 death row inmates.

The state Department of Corrections has previously used a mixture of three separate drugs to administer a lethal injection. Suppliers have been in short supply of the drug sodium thiopental, which is used as an anesthetic to render the inmate unconscious. This shortage is causing states to look for alternatives.

In May, Missouri opted for the use of a single-dose drug called propofol.

The drug, which has yet to be tested on human subjects, has left supporters and opponents of the death penalty at odds about the ability of the drug to administer executions.

The state Supreme Court recently declined to set the execution dates of six death row inmates until the new protocol has been resolved. The case for these six inmates has been sent back to the Cole County District Court for further consideration, but has yet to be heard in the district court. Attorneys in the case have also filed a motion for Attorney General Chris Koster to not dismiss the case.

Since the state Supreme Court handed down their decision, 21 more death row inmates have petitioned to have their execution dates delayed as well. These inmates are currently waiting for the state’s high court to hear their case.

Koster said in a statement that he is "disappointed (with the delay) and will continue to do all he can to expedite the protocol-challenge cases."

"It's a shocking turn of events because it's a drug that's used for short-term anesthesia purposes," said Kathleen Holmes, the State Coordinator of Missourians Against the Death Penalty. "This came out of nowhere, we're the first state to try to use propofol untested, so we just have a lot of concerns."

Propofol is known to cause pain on injection when used as a medical anesthetic, though there is some debate as to how much pain is associated with it. A lethal dose would use 15 times the amount used for medical purpose. This is a chief concern among those who oppose the use of propofol.

In his testimony, Dr. Mark Dershwitz of the University of Massachusetts argued that the lethal dose of propofol could cause intense pain for inmates.

"For many patients, the last thing they remember doing before falling asleep is screaming at the top of their lungs because propofol burns," Dershwitz said.

John Simon, one lawyer in the propofol case, said that the use of propofol is a step backward in human rights, and is the first time that there has been a movement away from a more humane death penalty.

"The new protocol, by using a drug which everyone familiar with it knows causes pain on injection is a step backward," Simon said. "It would be like replacing the electric chair with burning at the stake."

Richard Dieter, the executive director of the Death Penalty Information Center, said that if propofol was used properly, the inmate would be put to sleep and would not feel any pain. Though he argues that if the anesthetic is not administered properly, it has the potential to be just as painful as the firing squad or the electric chair.

"It does depend on the expertise of the people who perform it," Dieter said. "It's a bit of an experiment with human subjects who are often unwilling, which is always a dangerous area."

The case is still waiting to be heard in the Cole County District Court, and Koster has yet to choose whether or not to dismiss the case.