In addition, if this interaction did occur, then the pancuronium would be incapable of causing paralysis. Supporters of the death penalty state that the claim that the pancuronium prevents the thiopental from working, yet is still capable of causing paralysis, is not based on any scientific evidence and is a drug interaction that has never before been documented for any other drugs. Amnesty International, Human Rights Watch, Death Penalty Information Center, Reprieve, and other anti-death-penalty groups have not proposed a lethal-injection protocol which they believe is less painful. Supporters of the death penalty argue that the lack of an alternative proposed protocol is a testament to the fact that the pain felt during the lethal injection protocol is not the issue. Instead, supporters argue that the issue is the continued existence of the death penalty, since if the only issue were the painfulness of the procedure, then Amnesty International, HRW, or the DPIC should have already proposed a less painful method. Regardless of an alternative protocol, some death-penalty opponents have claimed that execution can be less painful by the administration of a single lethal dose of barbiturate. Supporters of the death penalty, however, state that the single-drug theory is a flawed concept. Terminally ill patients in Oregon who have requested physician-assisted suicide have received lethal doses of barbiturates. The protocol has been highly effective in producing a painless death, but the time to cause death can be prolonged. Some patients have taken days to die, and a few patients have actually survived the process and have regained consciousness up to three days after taking the lethal dose. In a California legal proceeding addressing the issue of the lethal injection cocktail being "cruel and unusual," state authorities said that the time to death following a single injection of a barbiturate could be as much as 45 minutes. Scientifically, this is readily explained. Barbiturate overdoses typically cause death by depression of the respiratory center, but the effect is variable. Some patients may have complete cessation of respiratory drive, whereas others may only have depression of respiratory function. In addition, cardiac activity can last for a long time after cessation of respiration. Since death is pronounced after asystole and given that the expectation is for a rapid death in lethal injection, multiple drugs are required, specifically potassium chloride to stop the heart. In fact, in the case of Clarence Ray Allen, a second dose of potassium chloride was required to attain asystole. The position of most death-penalty supporters is that death should be attained in a reasonable amount of time.