The trial moved to Los Angeles because of the publicity it received in the Bay Area.
A pre-trial hearing was held Tuesday, and by most accounts, it was Mehserle's team that came out the winner. They will get to use an expert witness to analyze the video of the shooting, and this witness sees things very differently than most of the general public sees, or even the prosecution sees.
The prosecution also has its own video analyst. Both lawyers said there could be two sets of dueling videos that jurors will have to watch frame by frame when the trial begins.
In an L.A. courtroom, for the first time ever, a Bay Area police officer is on trial for murder in an on-duty killing.
Outside the courthouse, the family of Oscar Grant hopes for justice.
"I'm confident that justice will be served. It's going to be served," said Wanda Johnson, Grant's mother.
During Tuesday's pretrial hearing, former Mehserle sat expressionless as video played of the moment he shot an unarmed Grant in the back. His lawyers say he meant to use his Taser.
Judge Robert Perry extended a gag order to now include Grant family attorney, John Burris. He also represents five of Grant's friends who witnessed the shooting at the Fruitvale station. Burris' final public statement came moments before he learned it would be his last of the trial.
"My inclusion on this witness list is a sideshow. It really has no evidentiary value," said Burris.
Defense attorney Michael Rains wanted Burris to take the witness stand, but the judge said that will not happen. Burris' own lawyer called it a defense strategy to keep the usually vocal Burris quiet.
"Quite clearly Mr. Rains wants to exclude his presence from the courtroom," said Carl Douglas, John Burris' attorney.
In a blow to the prosecution, Judge Perry also said Mehserle's lawyers could call on an expert witness to analyze video of the shooting. When broken down frame by frame, the expert testified the video doesn't show Mehserle or former BART Officer Tony Pirone striking Grant or his friends, but that it may have happened the other way around.
The father of two young men on the platform with Grant, criticized the judge's rulings.
"He's more in favor of putting Oscar Grant on trial and these young men on trial, than he is about putting Johannes Mesherle on trial. Johannes Mesherle is the one that committed the murder," said Jack Bryson, a father of one of the witnesses.
Mehserle remains out on $3 million bail. Security in this courthouse is extremely tight for this hearing. Two-hundred prospective jurors are expected to show up Wednesday. The lawyers are hoping all of the Los Angeles County residents have not heard of this case or let alone see any of the video that most Bay Area residents have seen by now.
The lawyers will likely spend the next three days questioning those jurors and then, because of the publicity surrounding the case and the high profile nature of it, the 18 jurors will then have to undergo a background check before opening statements next week.