An undated photo of Eduardo Santiago, the death-row inmate in the case where the Connecticut Supreme Court issued a ruling. (Connecticut Department of Correction via AP)

The Connecticut Supreme Court ruled Thursday that it would be unconstitutional to execute the remaining inmates on the state’s death row, effectively outlawing the death penalty in that state.

This decision comes three years after Connecticut abolished capital punishment while leaving death sentences intact for inmates already on death row. Lawmakers also kept the death penalty as an option for crimes committed before that 2012 bill was signed into law.

In the case before the state’s highest court, an inmate sentenced to death a decade ago argued that he should not be executed because his crime was committed before Connecticut prohibited future death sentences.

The justices agreed with that basic principle, saying the state could not execute someone who committed a crime before that same crime would no longer warrant a death sentence. But they also offered a larger indictment of capital punishment, describing it as a relic riddled with delays and bereft of purpose.

[How the death penalty continued its slow, steady decline in 2014]

The death penalty in Connecticut “no longer comports with contemporary standards of decency and no longer serves any legitimate penological purpose,” Associate Justice Richard Palmer, joined by three other justices, wrote for the court.

Palmer listed a series of issues with the death penalty, including racial and other biases “that likely are inherent” in how death sentences are handed down and the unlikelihood that Connecticut’s death row inmates would ever be executed.

As a result, he ultimately wrote that any execution “would violate the state constitutional prohibition against cruel and unusual punishment.”

In one of three dissenting opinions, Chief Justice Chase T. Rogers called the majority opinion’s analysis “fundamentally flawed” and “based on a house of cards, falling under the slightest breath of scrutiny.”

“I can only conclude that the majority has improperly decided that the death penalty must be struck down because it offends the majority’s subjective sense of morality,” she wrote.

[The Washington state Supreme Court justice who stepped down to protest the death penalty]

This ruling would seem to answer a lingering question since Connecticut became the third state in recent years to drop the death penalty but exempt people on death row from that change.

Since 2007, seven states have abandoned the death penalty, something done most recently by Nebraska earlier this year (where opponents are fighting to undo the change). But the question of what to do with the people on death row has been handled differently by different states.

In some states that abolished the death penalty recently, the governors or legislatures simultaneously commuted the sentences of inmates on death row, replacing death sentences with sentences of life in prison without parole. This happened in New Jersey in 2007, Illinois in 2011 and earlier this year in Nebraska (though that isn’t fully settled yet, because Doug Peterson, the state’s attorney general and a critic of the death-penalty ban, has said he will challenge the idea of changing death sentences to life sentences).

But in other states, lawmakers left a certain kind of limbo in place. Like Connecticut, both Maryland and New Mexico banned the death penalty going forward but exempted inmates who had been sentenced. Earlier this year, though, Maryland emptied its death row, as outgoing Gov. Martin O’Malley (D) followed through on announced plans to commute the sentences of the remaining inmates.

[Pennsylvania’s governor suspended the death penalty earlier this year]

New Hampshire remains the only state in New England with capital punishment still fully on the books, after legislators came within one vote of abolishing it last year.

On Thursday, Governor Dannel P. Malloy (D), who opposes the death penalty and signed the law outlawing it in 2012, said the state would continue looking to the courts for guidance on its death penalty ban.

“But it’s clear that those currently serving on death row will serve the rest of their life in a Department of Corrections facility with no possibility of ever obtaining freedom,” he said in a statement.

Malloy added: “Today is a somber day where our focus should not be on the 11 men sitting on death row, but with their victims and those surviving families members. My thoughts and prayers are with them during what must be a difficult day.”

State Senate Minority Leader Len Fasano (R) was critical of the justices, who he said in a statement “stepped way out of line and wrongfully took on the role of policymakers.”

[Federal judge says California’s death penalty system is unconstitutional]

The remaining inmates on Connecticut’s death row inmates are held at the Northern Correctional Institution in Somers, not far from the border with Massachusetts. Executions, if they ever took place, were to be carried out by lethal injection, according to a Department of Corrections policy issued last year.

“This decision reflects an evolving norm against the death penalty,” David McGuire, legislative and policy director of the American Civil Liberties Union of Connecticut, said in a statement. “There are better ways to punish.”

Connecticut has executed only one inmate since the U.S. Supreme Court reinstated the death penalty in 1976. The state put serial killer Michael Ross to death in 2005 after he dropped his appeals.

The state came close to abolishing the death penalty in 2009, but Malloy’s predecessor, M. Jodi Rell, vetoed a bill that year that would have eliminated the practice.

Her decision came as the state was still grappling with a horrifying home invasion in the state two years earlier. In a savage crime that drew widespread attention, two men broke into a family’s home before sexually assaulting a woman, Jennifer Hawke-Petit, and her 11-year-old daughter, Michaela. The two men also beat the girl’s father, William, before killing Jennifer, Michaela and the couple’s 17-year-old daughter, Hayley.

Both men accused in the case — Joshua Komisarjevsky and Steven Hayes — were convicted, found guilty and sentenced to death, a penalty that now appears to have been vacated.

Rell referenced that attack in her 2009 letter announcing the veto, and the crime was cited as the reason lawmakers compromised in 2012, abolishing the death penalty while keeping it in place for crimes already committed.

“I never thought it would happen, that we would see them die, but I always thought that there should be a punishment that fits the crime,” Cindy Renn, Jennifer’s sister, told the Hartford Courant of the two men. “I don’t think that will ever happen now in this case.”

In a statement, William Petit said the justices “disregarded keystones of our governmental structure such as the separation of powers and the role of the judicial precedent” in the decision.

The two men convicted of the attacks in the Petit home were cited in the Connecticut Supreme Court’s majority opinion as well as the chief justice’s dissent. Rogers wrote in her dissent that it was fair to assume that home invasion, a recent and prominent horror, could have helped lawmakers believe that there are crimes worthy of a death sentence.

But Palmer, in his opinion, states that “it would not be constitutionally permissible to execute [inmates]….merely to achieve the politically popular end of killing two especially notorious inmates.”

When the state did abandon the death penalty in 2012, public opinion was solidly in favor of keeping the practice for anyone convicted of murder but evenly divided on how to actually punish such people.

That year, a Quinnipac University poll found that 62 percent of people said they supported the death penalty for convicted murderers, compared to 30 percent who opposed it. However, when asked to choose between a death sentence or life in prison without parole for convicted murders, 46 percent of people favored each choice.

In the ruling this week, Palmer highlighted larger questions about the death penalty that were recently raised by U.S. Supreme Court Justice Stephen G. Breyer, who was joined by Justice Ruth Bader Ginsburg in a dissent questioning whether capital punishment itself violated the Eight Amendment.

That dissent was cited in the new Connecticut Supreme Court ruling, which pointed to, among other things, Breyer’s point about how likely it is the current system means someone innocent can be executed. (Most American, regardless of whether they support or oppose the death penalty, are in agreement that an innocent person can be put to death.)

Death penalty observers said that Breyer’s dissent, delivered during a case upholding Oklahoma’s lethal-injection protocol earlier this year, was likely to reverberate through other cases considering the constitutionality of the death penalty.

Breyer had also asked whether a delay-ridden death penalty system (death row inmates nationwide have spent an average of 14 years under their sentences) was still serving a legitimate penological purpose before going on to question the idea that capital punishment can deter future crime.

[Innocent man who spent 30 years on death row died hours before U.S. Supreme Court justices cited him]

Palmer was roundly dismissive of the idea of capital punishment as a deterrent, particularly if future criminal acts cannot be punished with an execution. He noted that despite thousands of murders have been carried out in the state over four decades, only one person has been put to death, and goes on to say that he doesn’t think eliminating the death penalty would lead to sudden lawlessness.

“We very much doubt that the citizens of Connecticut, learning that the death penalty has been abolished, will somehow infer that they can now rape, pillage, and exceed the speed limits with impunity,” Palmer noted.

The inmate in this case, Eduardo Santiago, was convicted of murdering someone in 2000. The case is State of Connecticut v. Eduardo Santiago.

RELATED:

‘It was fundamentally unfair.’ A prosecutor apologizes for his role in putting an innocent man on death row

Nebraska lawmakers abolished the death penalty earlier this year

Justices Breyer and Ginsburg: ‘It is highly likely’ the death penalty is unconstitutional

Can the death penalty be abolished?

Federal judge says California’s death penalty system is ‘unconstitutional’

A look at three executions that went awry last year

This post has been updated multiple times. First published: 12:02 p.m.