The Department of Justice said it will seek the death penalty for Dylann Roof, the white man accused of killing nine black parishioners in a shooting rampage at a historic church in Charleston last June. (Reuters)

Capital punishment in the United States is on the wane. Fewer people, 49, were sentenced to death in 2015 than in any year since the Supreme Court reauthorized the ultimate sanction in 1976; only 28 were executed, the fewest in 20 years.

States find it harder to obtain lethal-injection drugs, especially now that pharmaceutical giant Pfizer has barred the use of its products. A recent Supreme Court ruling overturned the death sentence of a black man in Georgia on the grounds that prosecutors improperly kept African Americans off the jury.

A death-penalty abolitionist, Sen. Bernie Sanders (I-Vt.), has given Hillary Clinton a run for her money in the Democratic presidential race; she, in turn, has voiced only qualified backing for capital punishment. And polls show downward movement in support for the death penalty.

Given all this, the Obama administration, perhaps the least favorable to capital punishment in recent memory, might not have sought the death penalty against Dylann Roof, the young white supremacist charged in the massacre of nine black men and women as they prayed in a South Carolina church a year ago.

But on May 24, Attorney General Loretta E. Lynch announced that the Justice Department would urge execution for Roof — and the reaction from capital punishment’s opponents has been conspicuously muted.

The National Coalition to Abolish the Death Penalty put a protest on its Facebook page. Sanders issued a generic statement of disapproval through his spokesman, but only in response to a question from Huffington Post. That’s about it.

Some crimes are so ghastly that even death-penalty skeptics find it hard, or at least inopportune, to challenge the moral intuition that calls for capital punishment; thus, there will probably always be a death penalty in the United States, as long as that moral intuition remains widely felt, and as long as the people can and will express it through democratic institutions.

Agreeing with South Carolina’s prosecutors, who are also seeking death for Roof, Lynch determined that his cold-blooded, racially motivated slaughter, coupled with his lack of remorse, amply fulfilled the Justice Department’s stringent criteria for invoking this rarely used power.

Two of the most popular arguments against the death penalty — its alleged disparate impact on black killers of whites, and the risk of condemning an innocent person — patently don’t apply to Roof.

All that would remain is a pure moral objection; that’s Sanders’s position, and a perfectly honorable one. Notwithstanding much commentary, however, it is not the view of most Americans, or even close.

Support for the death penalty in murder cases still beats opposition 61 percent to 37 percent in the most recent Gallup poll. Sixty-seven percent said the death penalty is applied either the “right amount” or “not enough,” and 53 percent to 41 percent the public agrees it is applied “fairly.”

What’s really happening is that overall support has ebbed from an anomalous high in the ’90s, when violent crime was also unusually high. As crime waned, so did the punitive backlash, and support for the death penalty settled back to normal levels. Since 1936, support has fallen below 50 percent in the Gallup poll only four times; only in 1966 did opposition lead, 47 to 42.

To be sure, death-penalty sentiment has become partisan along with everything else; now only 40 percent of Democrats favor it, as opposed to 71 percent of Democrats in 1995 and 77 percent of Republicans today, according to the Pew Research Center.

Hence Clinton’s equivocations. She can’t repudiate the federal death-penalty expansion during her husband’s administration, including the law Lynch is wielding against Roof, and, unlike Sanders, Clinton doesn’t have the luxury of running to the unrealistic left of the November electorate.

In a November candidates’ forum, she expressed “hope” that the Supreme Court would somehow rid state death penalties of their lingering flaws, while preserving the federal version, in which she has “much more confidence,” to deal with “particularly heinous crimes . . . like terrorism.”

She cited Timothy Mc­Veigh, a Roof-like domestic terrorist against whom the Clinton Justice Department successfully pursued the death penalty for the 1995 bombing in Oklahoma City that killed 168 people, including 19 children.

(Responding to my query, Clinton spokesman Brian Fallon confirmed that she agrees with the Justice Department decision on Roof.)

Clinton left open obvious and difficult questions, starting with where to draw the line between the worst of the worst and merely bad, murderers.

She was, in short, wrestling with the dilemmas facing any society that would entrust such life and death decisions to the people — voters, legislators, jurors — rather than abolishing capital punishment for all cases, even for terrorism and genocide, as the European Union has done.

It was that rare moment when Clinton seemed to be saying something that both she and most Americans really think.

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