The Supreme Court on Wednesday struck down a law that allows the execution of people convicted of a raping a child.

In a 5-4 vote, the court said the Louisiana law allowing the death penalty to be imposed in such cases violates the Constitution's ban on cruel and unusual punishment.

"The death penalty is not a proportional punishment for the rape of a child," Justice Anthony Kennedy wrote in his majority opinion. His four liberal colleagues joined him, while the four more conservative justices dissented.

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.

Texas joined the short list of states that sought the death penalty in some child rape cases in 2007. A key initiative of Republican Lt. Gov. David Dewhurst, the Legislature approved the death penalty for offenders who are twice convicted of raping children under 14, although legal experts predicted then it would be unconstitutional.

Victim advocates also warned the death penalty could do more harm than good if it led perpetrators to kill victims who may be the only witness to the crime.

Patrick Kennedy, 43, was sentenced to death for the rape of his 8-year-old stepdaughter in Louisiana. He is one of two people in the United States, both in Louisiana, who have been condemned to death for a rape that was not accompanied by a killing.

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

Forty-five states ban the death penalty for any kind of rape, and the other five states allow it for child rapists. Kennedy's case is the only time a state has sought to execute someone. Besides Texas, Montana, Oklahoma and South Carolina allow executions in such cases if the defendant had previously been convicted of raping a child.