Williams was convicted on four counts of covering up the shooting of a hired driver at his central New Jersey mansion more than seven years ago.
In 2007, the Hunterdon County Prosecutors Office disclosed that an investigator used a racial slur in reference to Williams in 2002.
Williams' attorneys argued in court Monday that the failure to disclose the remark before the trial, along with other actions by a former prosecutor, constitute misconduct.
The state argues that the slur had no effect on the cover-up convictions.
Williams is awaiting retrial on a reckless manslaughter count.