Forgive me if all this has been said before. Huge Elder Scrolls fan here, played at launch, payed the whole time it was pay to play, but only just now started playing again....
Title pretty much says it all. The justice system strives to bring more "realism" and authentic Elder Scrolls feel. So add open PVP but have it be the same as murder, and if you attack other players in town the guards attack you to "keep the peace", out of town you get a bounty, etc, etc.
Also give me my damn thieves guild and dark brotherhood and tie it all in. Maybe some type of overall versus system between criminal and just players. Or mages/fighters vs thieves/brotherhood.