Taken to the extreme, we could have an impartial legal system putting in prison criminals from an even mix of society, and then the president pardoning everyone from the majority group, leaving in prison only the minorities.
And how would you call a justice system, so complicated and convulted and therefore expensive that poor people (from minorities) don't really stand a chance to get their justice there?
Obviously Ross was not in that group, but I see presidential pardon as a potential tool to counter the flaws of the justice system.
You want a majority to be able to decide who gets punished and who goes free, and even the best designed laws will have unforseen consequences. If the majority is 'evil', well there's just not all that much that can be done in a democracy. Yes it would be better to live in a dictatorship of the most virtuous person in existence, but if you ever figure out how to do that please let me know.