In a 5-4 decision, the court struck down a Louisiana law Wednesday that allows rapists to be executed if their victims are children.

Louisiana's Republican governor denounced the ruling. Democratic presidential candidate Barack Obama and his GOP rival John McCain said they, too, disagree with it.

The ruling disappointed Utah state Rep. Carl Wimmer, R-Herriman, who had hoped to introduce legislation in Utah to make the worst sex crimes against children punishable by death. Utah is among 44 states where rape is not punishable by the death penalty.

"I have to decide what I could pass that would pass constitutional muster," Wimmer said Wednesday. "I'm so dismayed by the court's decision. It's an injustice to children," he said.

The decision added a wrinkle to the court's death penalty law, further limiting who may be executed in the same term it upheld executions by lethal injection. The outcome in the lethal injection case rested partly on the rationale that because capital punishment itself is constitutional, there must be some way to carry it out.

But Justice Anthony Kennedy, writing the majority opinion Wednesday, said that however devastating the crime to children, "the death penalty is not a proportional punishment for the rape of a child." His four liberal colleagues joined him, while the four more conservative justices dissented.

Wednesday's ruling spares the only people in the U.S. under sentence of death for child rape - two Louisiana men convicted of raping girls ages 5 and 8.

There has not been an execution in the United States for a crime that did not also involve the death of the victim in 44 years, a factor that weighed in Kennedy's decision.

Rape and other crimes "may be as devastating in their harm, as here, but 'in terms of moral depravity and of the injury to the person and to the public,' they cannot be compared to murder in their 'severity and irrevocability,' " Kennedy said, quoting from earlier decisions.

The victim in the case decided Wednesday was an 8-year-old girl raped by her stepfather at their home in Harvey, La., outside New Orleans.

Angry Louisianans who backed the law said the court was out of touch.

"The opinion reads more like an out-of-control legislative debate than a constitutional analysis," said Louisiana Gov. Bobby Jindal, a Republican. "One thing is clear: The five members of the court who issued the opinion do not share the same 'standards of decency' as the people of Louisiana."

Obama said the decision's blanket prohibition on punishing the rape of a child by death went too far. McCain called it "an assault on law enforcement's efforts to punish these heinous felons for the most despicable crime."

"That there is a judge anywhere in America who does not believe that the rape of a child represents the most heinous of crimes, which is deserving of the most serious of punishments, is profoundly disturbing," McCain said in a statement.

The Supreme Court banned executions for rape in 1977 in a case in which the victim was an adult woman.

Forty-four states prohibit the death penalty for any kind of rape, and five states besides Louisiana have allowed it for child rapists -Georgia, Montana, Oklahoma, South Carolina and Texas.