RALEIGH – Critics of North Carolina’s death penalty seem perpetually puzzled about why the issue is still a live one, so to speak.

In their minds, the question of capital punishment is settled. It is ineffective, costly, and morally wrong. It is ineffective because it doesn’t deter homicides, most of which don’t reflect careful calculation of the odds of apprehension, conviction, and execution. It is costly, to the tune of millions of tax dollars spent on both sides of the appeals process. And it is wrong because the state should not be in the business of taking a life.

I understand these arguments, but find them wanting – as do most North Carolinians, and indeed most of the residents of other states and countries that don’t execute murderers. Most of us still believe that there are some crimes so heinous that no penalty short of execution is a just one.

Most of us also believe that the prospect of execution deters at least some potential murders – those committed by thugs who would be otherwise tempted to slay their rape or robbery victims to eliminate witnesses, for example, or those tempted to shoot it out with law enforcement officers. And most of us believe that because of clear benefit of justice, and the possible benefit of deterrence, capital punishment is a worthwhile expenditure of millions of tax dollars.

Recognizing that they had failed to make their case on the fundamentals, death penalty foes turned to other avenues to accomplish their goals. They challenged the legality of particular methods of execution, such as lethal injection, and manipulated the occupational licensing laws to establish a de facto moratorium.

More significantly, they reintroduced the idea of racial discrimination. The old idea that black murderers were more likely to be executed that white ones, all other things being equal, had long ago been demonstrated to be false. No matter how they tortured the data, death-penalty foes could not show any pattern of racial discrimination among death-row inmates.

So they repositioned the argument: it isn’t the race of the perpetrator that matters, they now suggest, but the race of the victim. Those who kill whites are more likely to be executed than those who kill nonwhites, regardless of the race of the killer.

As I have previously pointed out, this latest argument contains a problematic implications for liberals: the more people care about and place a value on murder victims, the more they favor executing the murderers. I think that is probably correct, and morally praiseworthy. Do liberals agree? Presumably not.

But there is another problem with the argument: its empirical foundation is not as solid as death-penalty foes would have you believe. The problem lies in ensuring that no other variables besides the race of the victim can explain the apparent disparity. There are good reasons to doubt that past studies have controlled for all alternative explanations, and former Forsyth County District Attorney Tom Keith strengthened the case for skepticism with an op-ed published yesterday in the Winston-Salem Journal.

Referring to one of the two major studies death-penalty foes have cited as evidence for racial bias in North Carolina executions, Keith and coauthor Stanley Young observed:

State law lists the aggravating factors necessary for a homicide to be punishable by death. In 2009, death-penalty opponents using the sealed Chapel Hill study contended that African-Americans who kill white victims receive the death penalty in 5.1 percent of the cases, versus 3.5 percent for whites for killing an African-American victim. This was an inappropriate comparison. Instead, the anti-death-penalty advocates should have only used the data from the homicides with aggravating circumstances.

When comparing only homicides with aggravating circumstances, both races have the same approximate 10 percent chance of receiving the death penalty in cross-racial homicides (African-American on white: 33 of 365 cases, or 9 percent; white on African-American: 5 of 45, or 11 percent). This is based on the 2009 Chapel Hill study, which was only recently unsealed…

Homicide racial patterns were studied by Joseph Katz, the statistician in the seminal U.S. Supreme Court McCleskey decision, which held that statewide statistics were not appropriate to prove racial discrimination in a death-row inmate’s case. Katz found that in Georgia’s cross-racial homicides, each race committed aggravated homicides at vastly different rates. For example, African-Americans on death row committed an armed robbery during their interracial homicides 67 percent of the time, versus 22 percent for whites; and African-Americans committed an execution-style interracial murder 33 percent of the time, versus 12 percent for whites.

This is significant since armed robberies and execution-style murders in most states and in North Carolina are aggravating factors that qualify a murderer for the death penalty.

Anti-death penalty activists like to tell themselves that the policy debate over capital punishment is over. They are wrong. They also like to tell themselves that Gov. Bev Perdue’s veto of the repeal of the Racial Justice Act means that the political debate over capital punishment is over.

Wrong again.

Hood is president of the John Locke Foundation.