... A small yet significant example from the world of sport.
Rugby union has for some time now been using video replays to assist referees in making difficult line-calls in important decisions. Now, whenever a referee is unsure as to whether, for example, the ball has been correctly grounded or not, he simply signals for the 4th umpire, who watches the television replays and makes the decision. The system is widely viewed to have been a success, ensuring the "justice" of controversial decisions.
However, like all rules, a balancing act is necessary; here between the drive for "justice" and the wish to avoid impeding overly the flow of the game. Thus, the use of video replays has been limited to examination of what happens in the scoring area only. Other calls, regardless of importance, do not fall within the jurisdiction ratione materiae of the 4th official.
Let me illustrate the essential arbitrariness of this rule, and the concomitant denial of justice. Consider the following example, selected at random from yesterdays international matches: Scotland lead France, in Paris, 9-6 with 10 minutes to go. Suddenly, Scotland break away, and think they have scored - a try that would almost certainly win them the game. However, the touch judge calls them back, claiming that the player had put his foot out of play before grounding the ball. Video replays prove that this simply was not true; however, because the line in question was the touch line and not the try line, the decision cannot be referred to the video referee, and the faulty decision stands. Five minutes later, the French get a lucky break and score a try - the validity of which this time is, ironically, confirmed by the 4th official - which seals the victory for them. The two cases seem identical in terms of justice - how can the simple question of which line is involved be ethically significant? However, pragmatic considerations intervene in a manner that can only be described as essentially arbitrary, and Scotland lose (despite, it should be said, a heroic performance).