Obama slams the U.S. Supreme Court for outlawing execution for child rapists

"I have said repeatedly that I think that the death penalty should be applied in very narrow circumstances for the most egregious of crimes," Obama said at a news conference Wednesday.

"I think that the rape of a small child, 6 or 8 years old, is a heinous crime and if a state makes a decision that under narrow, limited, well-defined circumstances the death penalty is at least potentially applicable that that does not violate our Constitution."

The court's 5-4 decision Wednesday struck down a Louisiana law that allows capital punishment for people convicted of raping children under 12, saying it violates the Constitution's ban on cruel and unusual punishment.

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The ruling spares the only people in the U.S. under sentence of death for that crime - two Louisiana men convicted of raping girls 5 and 8.

It also invalidates laws on the books in five other states that allowed executions for child rape that does not result in the death of the victim.

Obama's Republican rival, John McCain, also criticized the court's decision, calling it "an assault on law enforcement's efforts to punish these heinous felons for the most despicable crime."

Obama said that had the court "said we want to constrain the abilities of states to do this to make sure that it's done in a careful and appropriate way, that would have been one thing. But it basically had a blanket prohibition and I disagree with that decision."

Obama has long supported the death penalty while criticizing the way it is sometimes applied.

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As an Illinois legislator, he helped rewrite the state's death penalty system to guard against innocent people being sentenced to die.

The new safeguards included requiring police to videotape interrogations and giving the state Supreme Court more power to overturn unjust decisions.

He also opposed legislation making it easier to impose the death penalty for murders committed as part of gang activity.

Obama argued the language was too vague and could be abused by authorities.

But Obama has never rejected the death penalty entirely. He supported death sentences for killing volunteers in community policing programs and for particularly cruel murders of elderly people.

"While the evidence tells me that the death penalty does little to deter crime, I believe there are some crimes - mass murder, the rape and murder of a child - so heinous, so beyond the pale, that the community is justified in expressing the full measure of its outrage by meting out the ultimate punishment," he wrote in his book "The Audacity of Hope."