The lawyer for the family of a 22-year-old man who was shot in the back and killed in Oakland last year by a transit officer said a judge's pre-trial decision to allow evidence about the victim's criminal record, could hurt the prosecution's case.

Defense attorneys will be permitted to tell the jury in the criminal trial that the shooting victim, Oscar Grant, fled from police during a traffic stop in 2006, the Los Angeles County Superior Court judge ruled.

"It should have a negative impact on the jury,"attorney John Burris told Youth Radio about the decision. Burris represents Grant's mother in a $50 million civil lawsuit that is set to follow the upcoming murder trial. "The impact could be to reduce the murder to manslaughter," he said.

The ruling by Judge Robert Perry may influence a central question jurors will be asked to consider: was Grant resisting arrest on the night he was killed?

The shooting took place on January 1, 2009, at a Bay Area Rapid Transport station in East Oakland's Fruitvale neighborhood. BART officers were dispatched to the station after reports of a fight on board the train that Grant was traveling on. BART passengers used their cell phones and other handheld devices to take video and photos, which show Grant lying face-down on the station platform when BART officer Johannes Mehserle drew his gun to Grant's back and fired the shot that killed him. [Click here to watch footage of the scene and a Youth Radio interview with the witness who shot the video.]

Attorneys involved in the murder trial are prohibited from discussing the case outside the courtroom, because of a gag order.

According to The Campanil, a Mills College news service which is covering the murder trial from Los Angeles, BART officer Mehserle's attorney asked to include Grant's criminal background as a way to establish a "character trait" for resisting arrest.

During a 2006 traffic stop, Grant reportedly ran from San Leandro officers, but was caught and shot with a taser gun. According to the Associated Press, the police report says that he resisted arrest as officers tried to put handcuffs on him, and that a .380 pistol was found a couple of feet from him. Grant was charged with gun possession and sentenced to to 16 months in state prison.

"I must allow some evidence of this prior incident," Judge Perry said in his ruling, according to the Associated Press. "The fact he resisted before, and the way he did it before" is important.

In an interview, John Burris said he disagreed with the ruling.

"I don't think his background has any relevance to Mehserle," Burris said. "Mehersle did not know him during the time of the fatal shooting."

Burris said the prosecutor for the murder trial, David Stein, is focusing on the videos captured by passengers the night Grant was shot and killed. Some of the videos clearly captured the sound and the moment Mehserle shot Oscar Grant while lying down with his hands behind his back. He said the jury will see that Grant was not resisting arrest at the time he was shot. Burris also expressed concern over having a third person interpret the video--a possibility that the judge hasn't ruled out.

The racially charged case--Grant was black, Mehserle white--sparked several waves of protests in Oakland last year. The trial was moved from Alameda County at the request of Meserle's attorney. It was moved in November to Los Angeles after the case received widespread local media coverage in the Bay Area.

Jury selection is expected to begin June 1st, with opening statements on June 14th.