Dennard, 23, who is scheduled to be sentenced on April 11, could escape jail time if he is given probation for the felony charge and misdemeanour.
Dennard was charged with punching a policeman outside a bar in Lincoln, Nebraska, last April 21 just days before the University of Nebraska player entered the 2012 NFL Draft.
The incident led to Dennard slipping to the seventh round of the draft, where he was selected by the Patriots.
He made six starts for New England last season and finished with three interceptions returning one for a touchdown.
