When people are accused of a crime it is absolutely necessary for that person and any victims to accept that they have had a fair trial. It is also absolutely necessary that the sentence is fair and proper. I believe that this can only happen if someone is mentally alert.
Time and time again we see Judges making really poor and obscene decisions, letting rapist and paedophiles off with little more than a warning. I believe that their poor decision making is sometimes age related. Younger Judges are more mentally alert than their older counterparts and would make better decisions.