On Thursday a jury found former BART police officer Johannes Mehserle guilty of involuntary manslaughter in the death of Oscar Grant.
But jurors also found him guilty of a gun enhancement charge which could add up to 10 more years to his sentence.
Legal experts say the enhancement charge is intended to give extra punishment to criminals who use a gun during a crime, but Mehserle was a police officer at the time, who was supposed to carry a gun.
"I'd try to make it very simple for the judge; I would say, 'Judge you know the facts. On these facts these two verdicts cannot stand. You should let the involuntary manslaughter conviction stand but you should find that the gun enhancement is contrary to the facts and the law and either modify the verdict or grant us a new trial,'" ABC7 legal analyst Dean Johnson said.
Mehserle's attorney has already asked for the August 6 sentencing date to be delayed so he can review the arguments.
Mehserle is expected to remain in custody until he is sentenced.