I'm president of Japanese Federaetion of Bar Assosiation, in Japanese, Nippon benngoshi Renngoukai. I'll tell you the reason why we need public opinion on the trial.
As you know, lay judges decide whether the defendant is guilty or not guilty and the sentence if they thought the defendant is guilty. It is essential to punish criminals for our safety life, but that's the fact that even innocence citizens were punished in the past. Judge's sence is different from that of normal citizen. Actually, there was a case clearly not guilty defendant was told guilty.Some says that that could avoid if normal people were judges. This is a serious problem because the judgement greatly affect people's life. If the defendant doesn't comit crime, the sentence would deprive his or her freedom or rights.
To avoid such mistakes, we need commonsencial citizen's view.Moreover, by participating trials, people would understand more about law than now, and would grow the trust toward judiciary. I know it is difficult task for people to make a decision which determine someone else's fate, but we need common sence to improve the quality of trials.