WASHINGTON (AP) — Supreme Court Justices Stephen Breyer and Ruth Bader Ginsburg declared for the first time Monday that they believe it is "highly likely" that the death penalty is unconstitutional.

In doing so, they joined three other justices over the years who came to harbor serious doubts about capital punishment after years of reviewing death penalty cases at the high court.

The court's modern death penalty cases began in 1972, when a fractured court struck down capital punishment laws nationwide in Furman v. Georgia. But four years later, a majority of the justices voted to restore the death penalty in a case called Gregg v. Georgia. The court approved new capital punishment laws that had been drafted in response to Furman, aimed at creating more uniformity in the application of the death penalty and eliminating racial bias.

At the time of the Gregg decision, only two justices, William Brennan and Thurgood Marshall, announced their opposition to the death penalty.

Three other justices have spoken out on the topic:

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HARRY BLACKMUN

Justice Harry Blackmun started out his Supreme Court career voting to uphold the death penalty. In 1972, just two years after joining the court, he dissented when his colleagues voted to abolish capital punishment. He voted with the majority four years later to return the death penalty.

But in February 1994, after more than two decades on the court and only a few months before his retirement, Blackmun announced he had changed his mind.

"From this day forward, I no longer shall tinker with the machinery of death," Blackmun, then 85, wrote in announcing his opposition.

It was Breyer who took Blackmun's seat on the court.

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LEWIS POWELL

Like Blackmun, Justice Lewis Powell voted in support of the death penalty in 1972, the year he joined the court, and again in 1976.

Powell retired from the court in 1987 at the age of 79 and announced his opposition to the death penalty only after he left the court.

"I have come to think that capital punishment should be abolished," he told his biographer, adding it "serves no useful purpose."

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JOHN PAUL STEVENS

Justice John Paul Stevens had to confront the issue of the death penalty head-on in his first year as a justice. He joined the court in December 1975, and one of his first votes was to join with the majority of his colleagues to reinstate the death penalty.

But over more than three decades as a justice, Stevens' views shifted. In 2008, he concluded that the death penalty represents "the pointless and needless extinction of life with only marginal contributions to any discernible social or public purposes." Stevens left the court two years later, in 2010, at the age of 90.

Stevens has written and spoken about his opposition to the death penalty. In his 2014 book, "Six Amendments: How and Why We Should Change the Constitution," he explains why he believes the Constitution should be changed to ban the death penalty.

Stevens, now 95, was in the courtroom Monday and listened to Breyer announce his and Ginsburg's views. Both Breyer, 76, and Ginsburg, at 82 the court's oldest serving justice, have spent more than two decades on the court.

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Follow Jessica Gresko at https://twitter.com/jessicagresko.