FAYETTEVILLE, N.C. — Lawyers for a Cumberland County man on North Carolina's death row for a 1991 murder argued Wednesday that the jury selection in his trial was racially biased and his sentence should be commuted to life in prison.

Marcus Robinson's case is the first under the 2-year-old Racial Justice Act, which allows death row inmates to use statistical evidence to challenge their sentences. Robinson, who is black, was convicted of robbing and killing a white teenager.

Superior Court Judge Gregory Weeks isn't expected to issue a ruling in the case for at least two months. If he agrees that racial bias played a role in the case, Robinson would be re-sentenced to life in prison without the possibility of parole.

Defense attorney Jay Ferguson told Weeks that there is a "stark disparity" in the number of blacks struck from serving on juries as opposed to whites.

When all other variables are disregarded -- views toward death penalty, criminal record or personal hardship -- prosecutors across North Carolina strike blacks from juries twice as often as whites, Ferguson said. The ratio is even higher in Cumberland County, he said.

"In district after district after district after district, there is a gross disparity of striking African-American jurors as opposed to all others," he said.

Two blacks served on Robinson's jury.

A study by Michigan State University shows that a defendant in North Carolina is 2.6 times more likely to be sentenced to death if at least one of the victims is white. The study also showed that blacks were more than three times as likely to be dismissed from juries in the state than people of other races.

Tye Hunter, another defense attorney, called the disparity between black and white jurors "a systemic problem."

"We're all responsible for what has happened," said Hunter, who works with the Durham-based Center for Death Penalty Litigation. "It needs to be fixed, and I'm satisfied that it's not going to be fixed until there are consequences."

Prosecutors argued Tuesday that the Michigan State study cannot be trusted because it was based on a too limited sample of death penalty cases to provide meaningful results.

The Fayetteville Observer reported that Union County prosecutor Jonathan Perry said in his closing argument that the statistical technique used to produce the study's results, called logistic regression, is not able to detect numerous nonracial reasons that a person might be peremptorily struck from a jury.

Perry, who is helping the Cumberland County District Attorney's Office fight the claim from Robinson, handled most of the testimony from statistics experts in the 2 1/2-week hearing.

Christopher Cronin, a political scientist at Methodist University, testified Monday that blacks are more likely than other races to be politically liberal, oppose the death penalty and mistrust the criminal justice system. Such ideology could explain the results of the Michigan State study, he said.

Under cross-examination, Cronin said it was wrong to assume that every black person would have the same opinion on the death penalty or any other issue.

Hunter argued Wednesday that prosecutors kept white jurors on Robinson's jury even after they cited personal hardships for serving, but they struck blacks who had similar circumstances. Every potential black juror in the case said they could be fair in determining a sentence, he said.

If he polled all 7,000 jurors in the Michigan State study, Hunter said, "I could give you a non-racial reason to eliminate every single one of them."

Rob Thompson, another Union County prosecutor, said Wednesday that black jurors struck in the Robinson case had clear objections to the death penalty or unreasonable requirements for a conviction.

"They have numbers. They do not have evidence of purposeful discrimination," Thompson said, noting that Robinson's attorneys believe numbers alone prove racism.

Cumberland County prosecutor Cal Colyer also pointed out that defense attorneys often strike potential jurors who support the death penalty.

State lawmakers tried last year to roll back the Racial Justice Act, but Gov. Beverly Perdue vetoed the effort and an override vote fell short. A House committee is now looking at ways to narrow the scope of the law.

"The goals may be admirable with respect to this legislation, but it is an insult to the prosecution, to the judges of this state," Colyer said.