Justin Ross Harris deserves a new trial in the hot-car murder case involving his son because “an avalanche of evidence” of his carnal behavior was wrongly put before his jury, his lawyer argued Tuesday.

“The sexual messaging acts did not make it more probable that Mr. Harris would intentionally kill his child,” attorney Mitch Durham told the Georgia Supreme Court.

At the outset of the arguments, held virtually, Chief Justice David Nahmias disclosed he has COVID. He said his symptoms are mild and attributed that to being fully vaccinated.

At the outset of the arguments, held virtually, Chief Justice David Nahmias disclosed Tuesday he has COVID. He said his symptoms are mild and attributed that to being fully vaccinated. (DAVID BARNES / DAVID.BARNES@AJC.COM)
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During the session, Nahmias and Justice Nels Peterson repeatedly questioned Cobb County prosecutor Linda Dunikoski whether all the evidence about Harris’ deviant sexual behavior should have been allowed into evidence.

All of that evidence made the same point: “This is a terrible person,” Peterson said. “And I will say you did a remarkable job of proving he’s a terrible person. But proving he is a terrible person isn’t the same as proving he murdered his child.”

On June 18, 2014, Harris left his Cobb County home with his 22-month-old son Cooper to drop him off at day care before going to work at Home Depot. But Harris later told police he forgot to drop off Cooper and mistakenly left him in his car seat in the company parking lot.

In the ensuing hours, Cooper died of heatstroke. Harris told police he realized his mistake when, driving away from work, he noticed his dead son in his car seat.

Prosecutors said Harris intentionally left his son in his car to die. They contended he wanted to free himself of his marriage and pursue a child-free lifestyle with numerous sexual relationships.

A jury in Glynn County, where the 2016 trial was held because of intense publicity, found Harris guilty of murder. He was sentenced to life in prison without the possibility of parole.

A key issue for the justices to decide is whether evidence of Harris sexting with underage women and seeing prostitutes was so overly prejudicial he should get a new trial.

Nahmias and Peterson, both of whom asked most of the questions, appeared to agree that some of the evidence was relevant to establish a motive.

“But maybe messages with underage people, evidence of prostitutes and all of that was so much more prejudicial than it was probative,” Peterson said.

Nahmias wondered why it was necessary for the prosecution to take nine thumbnail-sized screen shots of Harris’ penis from his phone and blow them up into full-sized color photos for the jury to see.

“I have no idea why they made that decision,” Dunikoski said of the prosecutors who tried the case. She conceded that enlarging the photos was not relevant but argued they were not unfairly prejudicial in light of other evidence in the case.

Peterson later asked Dunikoski: If the court finds that some of the evidence of Harris’ sexual proclivities should not have been admitted, what is your best argument it wasn’t overly harmful?

“There is overwhelming evidence that he murdered his child and that comes from a number of things he did throughout that day,” Dunikoski replied.

But Nahmias quickly cut in, “You’re really going to say the evidence of intent here was overwhelming?”

“No, you’re absolutely right,” she responded. “I misspoke. ... Viewing the evidence as reasonable jurors would view it, there is a high probability the sexting messaging evidence did not contribute to the murder verdict.”

The court is expected to issue its decision in the coming months.