The man who fatally shot retired New Orleans Saints star Will Smith and wounded his wife after a traffic crash last year was sentenced Thursday to 25 years in prison for manslaughter, far less than the maximum prosecutors had called for.

Cardell Hayes faced up to 60 years if given consecutive maximum terms for manslaughter and attempted manslaughter, as prosecutors had urged. Instead, Judge Camille Buras gave him 15 years for shooting Racquel Smith in the legs, to be served at the same time.

Hayes, 29, will get a year of credit for the time he's already served since shooting one of the city's sports heroes in April 2016. State law requires him to serve 85 per cent of the sentence before becoming eligible for good-behaviour release, meaning he could be freed in roughly 20 years.

"If he was sentenced to 60 years, he probably could have died in jail. At least with 25 he has the opportunity to be reunited with his family," Hayes' lawyer, John Fuller, said outside court.

Racquel Smith said she is "extremely disappointed" at what she called the leniency of the sentence, given the violence of the crime and her family's pain and loss.

"This ordeal has been a nightmare for me and my family. There are no winners here today," her statement said. She praised prosecutors and police, and said she and their three children, Willie, Lisa and Wynter, will carry on Smith's legacy of love for his community.

"I will continue to shine my light for my Superman," she said.

'Egregious' sentence according to DA

Hayes, a beefy ex-semi-pro football lineman, lumbered to the stand with his arms and legs shackled, and broke down in tears Thursday as he talked of the impact on his 6-year-old son and his mother.

He looked at Racquel Smith and told her he wished the night had never happened. He insisted he was afraid for his life as Smith fired a gun at him, despite trial evidence and witness testimony indicating Smith never handled or fired his gun.

Later, under tough questioning by a prosecutor, he referred to the Smiths, saying, "I apologize for their loss."

Hayes' mother, Dawn Mumphrey, also testified, wailing and shaking as she pleaded for mercy and forgiveness.

"That's my baby," she cried. "Lock me up and give me my son back."

Assistant New Orleans District Attorney Laura Rodrigue dismissed the tears as a "desperate attempt" to gain sympathy, and hammered at Hayes' claim of self-defence. She referenced a 2016 recording of a prison phone conversation, played at trial, in which Hayes called Racquel Smith "a phoney" and Mumphrey also disparaged her.

"Cardell Hayes took the stand and flat-out lied. That's the most offensive part of this entire process," Rodrigue said. She added, "To reward a person for taking the stand and lying is egregious."