[Daryl Atkins]'s attorneys said yesterday they were heartened by the court's decision. "I'm confident that we proved last year that Daryl Atkins was mentally retarded," said Joseph Migliozzi, his lead counsel, who said he planned to visit Atkins to explain the ruling in person.

Eileen Addison, the commonwealth's attorney in York County, said she expects the decision to lead to another trial. "We will do it again," she said. "I don't believe Daryl Atkins is mentally retarded under any stretch of the imagination." Of his death sentence, she added: "Three juries have thought this is what he deserved."

Scott Sundby, a professor at Washington and Lee University School of Law, agreed that, in new areas of law, "there tends to be a learning curve and you tend to get more reversals in the beginning." But other factors may be at issue, too, he said. "This in part may reflect that the U.S. Supreme Court has in the last four to five years become more aggressive in reversing death sentences," he said. "It may be a trickle-down effect."