An Orleans Parish judge on Thursday handed a life prison sentence with no chance of parole to Jeremy Burse, who was 15 when he fired a single shot during a 2010 armed robbery attempt that ricocheted and fatally struck his friend, Anthony Davis, in the heart.

In doing so, Criminal District Court Judge Byron C. Williams found that Burse, now 21, was that “rare juvenile offender whose crime reflects irreparable corruption.”

That was the bar the U.S. Supreme Court set in 2012 in the case of Miller v. Alabama, deeming automatic life sentences unconstitutional for juvenile killers. The ruling requires hearings to decide which young killers warrant the harshest punishment allowed and which ones deserve a shot at parole decades down the road.

A Louisiana law drafted in response to the ruling says life sentences without the chance of parole for juvenile killers “should normally be reserved for the worst offenders and the worst cases.”

Judges have been left to decide which killers are “the worst,” based on factors laid out by the high court in a 5-4 decision that relied on the science of brain development to find that children differ from adults in their “diminished culpability and greater prospects for reform.”

In a Louisiana case, the Supreme Court ruled recently that the decision applied retroactively, making some 300 Louisiana convicts eligible for new sentencing hearings. The court suggested that states could save themselves trouble by banning life sentences without parole for juvenile killers. A nascent campaign to do just that is underway, advocates say.

In the meantime, the choice for Williams was whether to make Burse eligible for parole at age 50. For more than five hours, defense attorneys and prosecutors with District Attorney Leon Cannizzaro’s office sparred over whether the diminutive Burse, who sat shackled in orange prison scrubs, could be redeemed.

A jury in June 2013 convicted him of second-degree murder for a killing that prosecutors acknowledged was unintentional. Burse, a John McDonogh High School student, had gone with Davis and two friends to the Willowbrook apartment complex in New Orleans East on Sept. 10, 2010.

Burse and Davis planned to rob a security guard, Keenan Brisco, of his service weapon. Brisco refused to hand it over and ran. He was then shot by Davis, ballistics reports show. He survived, but Burse also fired. The bullet caromed, possibly off the ground, and struck Davis.

Ricky Stewart, a friend who was waiting in the car, testified that he saw Burse jump a gate after the shooting and run for the car. “He get in the car saying that he made a mistake, he shot a security guard, and then he jumped out and leave me in the car,” Stewart said.

Christopher Murell, an attorney for Burse, argued that he was far from a cold-blooded killer exhibiting what the Supreme Court described as “irretrievable depravity.”

Murell rattled off several spine-chilling murders committed by juveniles in New Orleans and beyond, saying, “This is clearly a case that falls on the end of the spectrum of the least culpable.”

Assistant District Attorney Laura Cannizzaro Rodrigue countered that Burse had shown no remorse to the family of his friend and that justice for the victims warranted giving Burse no chance at parole. She played jailhouse phone calls in which Burse sang homespun rap lyrics describing violence and adopting a persona, “J-Murda.”

“He seemed to brag about the crimes he committed and future crimes that don’t exist in reality but in his mind,” said forensic psychiatrist Dr. Michael Blue, a prosecution witness who evaluated Burse and found him “at elevated risk to engage in violent behavior in the future.”

Also testifying was a longtime teacher at the Orleans Parish jail, Jacalyn Moss. She praised Burse for his earnest study habits, self-motivation and politeness.

“Even after his conviction, the first thing he did was he said, ‘I’ve been convicted, but I want to continue working,’ ” Moss said. “Any type of disturbance in class, he was never a part of. Never ever, and this is most unusual, did I hear any foul language from him.”

The victim’s mother, Gilda Davis, cried out from the witness stand.

“I want to let you know my child matters to me! His life is worth something, too!” she said. “Our kids made the wrong decision in life. My child made a bad decision, and he’s not here.”

Although Davis was called as a prosecution witness, she said she feels for Burse and his family, as well: “It hurts for those families. It doesn’t matter if they never showed me any remorse.”

Only a handful of such hearings have taken place in Orleans Parish since the two Supreme Court rulings. In most of those cases, judges have handed convicted juvenile killers life without parole.

Williams did the same on Thursday. The judge said he was concerned that “when anyone picks up a gun, they should assume the consequences of that action.”

“In this particular case, an armed robbery led to the murder of Ms. Gilda Davis’ son. And following everything the court has heard, I am compelled to sentence Mr. Jeremy Burse to life imprisonment without parole, probation or suspension of sentence.”

Seconds later, Burse’s mother suffered a violent seizure, splaying out across a courtroom bench as a bailiff cleared the courtroom.

Follow John Simerman on Twitter, @johnsimerman.