A U.S. judge in New York Monday declared the federal death penalty unconstitutional. The ruling is expected to be appealed by the federal government.

U.S. District Judge Jed Rakoff called the Federal Death Penalty act "tantamount to state-sponsored murder of innocent human beings."

He ruled that people are not given enough opportunity to prove their innocence, creating a risk executing innocent people and denying the right to due process. This is the first time since 1994 that the Federal Death Penalty Act has been declared unconstitutional.

Although the decision does not affect state death penalty laws, it could halt federal executions in several states. U.S. District Court Judge Rakoff said he based his decision on recent studies of death penalty cases in state courts, which indicate that numerous innocent people have been sentenced to death.

Norman Olch is a law professor at New York's John Jay College of Criminal Justice. Professor Olch says that in the past, a national debate about the death penalty in the United States centered on ethical issues. Now he says science is fueling the debate.

"I think that the engine that at the moment is driving the increased dialogue about the death penalty is science," he said. "And I think one of the questions that the proponents of the death penalty, it seems to me, must answer is the question of the execution of the innocent. It simply has been shown recently that there are a number of wrongfully convicted people either on death row or serving long-terms of imprisonment."

The U.S. Supreme Court ruled last month that the execution of the mentally retarded is unconstitutional. Meanwhile, the U.S. States of Maryland and Illinois have declared moratoriums on executions pending review of the system. In the past, bias based on racial and geographic grounds in death penalty cases have been revealed.

New York's highest court is also reviewing a death sentence case for the first time in nearly 20 years.

Federal prosecutors, who are expected to appeal Judge Rakoff's decision, argue that no one sentenced under federal law has later been found innocent.

Two people have been executed under the 1994 Federal Death Penalty Act Oklahoma City bomber Timothy McVeigh and Juan Garza, convicted of murder related to drug smuggling.

Judge Rakoff made his ruling during pre-trial arguments in a case involving partners in a heroin ring, accused of torturing and killing an informant.