The nation has been treated in recent days to an unseemly spectacle: Arkansas has been champing at the bit to execute eight prisoners assembly line-style in the first mass execution since the death penalty was restored in 1976.

Opponents of the death penalty blasted the rush to death. The plan was to execute the eight over 11 days, with the death chamber booked twice a night for several of the killings. Rachel Maddow, the host of a nightly television program on MSNBC, even referred sarcastically to the planned executions as "doubleheaders."

The condemned made last-minute appeals as, notably, did McKesson Corp., the manufacturer of vecuronium bromide, one of the three drugs in the state's lethal cocktail. It argued, successfully at first and receiving a restraining order against the state, that its drug was intended only for medicinal use, and that use in executions would irreparably harm its reputation and bottom line.

Four of the prisoners received stays on reasons unrelated to McKesson's appeal, but the state Supreme Court reversed the restraining order on use of McKesson Corp.'s drug and Arkansas executed one of the prisoners just before midnight Thursday — four minutes before the prisoner's death warrant expired. Two more were executed on Monday night, within hours of each other. The state has been trying to beat the clock with execution of the remaining one because its supply of midazolam, the sedative in its lethal cocktail, is set to expire at the end of the month. Midazolam is suspected of being the culprit in several botched executions in other states, which saw prisoners gasping and writhing, in one case (in Arizona) for almost two hours. (The third drug in the Arkansas cocktail is potassium chloride.)

Opponents of the death penalty initially were heartened both by the temporary stays of the four, and the initial success of McKesson Corp.'s appeal, but this frenzy has obscured a central issue: whether the death penalty can ever provide equal justice under the law, the core principle of our judicial system.

Arkansas' neighbor, Louisiana, is a case in point. The Louisiana Law Review found in 2011 that a death sentence was 97 percent more likely for those whose victim was white as opposed to those whose victim was African American.

Further, University of Iowa professor David Baldus studied murder convictions in Georgia in the 1970s and 1980s and found vast racial disparities in sentencing. Baldus also studied 677 homicides in Philadelphia in the decade beginning in 1983 and, according to the Atlantic, "found that black defendants there were nearly four times likelier than white defendants to receive a death sentence for the same crimes."

The death penalty is also geographically biased. Nearly 1,200 people have been executed in the South since the death penalty was reinstated, compared with fewer than 200 in the Midwest, around 85 in the West and only four in the nation's most populous region, the Northeast.

In California, someone convicted of murdering a white person in a rural area is "more than three times more likely to be sentenced to death those convicted of killing blacks and more than four times more likely than those convicted of killing Latinos," according to researchers Glenn L. Pierce and Michael Radelet.

Worse, the Guardian reported in 2012 that a single local jurisdiction, Harris County, Texas, led the nation in death sentences, accounting for more than one-third of Texas' 305 death-row inmates and half of its 121 African-American death-row prisoners.

We also execute the mentally ill and disabled, although the Supreme Court has outlawed the practice. According to the Charles Hamilton Houston Institute for Race and Justice at Harvard University, 68 percent of those executed in 2015 suffered severe mental impairments.

The evidence that the death penalty has no deterrent value is compelling. The South had the most murders in 2014, despite having the most executions. Eighty-eight percent of American criminologists surveyed by researchers at the University of Colorado say the penalty is not a deterrent, while chiefs of police polled by R.T. Strategies, a public affairs group, said the death penalty was the least effective way to prevent violent crime. Another R.T. Strategies study, this one of police homicides over a 13-year period, found that the death penalty failed to afford law enforcement any additional protection.

The evidence shows that the death penalty will never provide equal justice under the law. It should be abolished.

Martin W.G. King is the retired senior writer at the National Crime Prevention Council in Washington.