But judges are there in part to balance out the amature nature of a jury.
Elizabeth's passage talks about people being too busy, the question of a jury's opinon in equal standing to a judges (jury verdicts being taken seriously), and the benefit of a jury being a better reflection of "current common sense."
But I would have a bigger concern as to how a jury would reach its decision. It takes so long for a group of Japanese people to decide where to eat for lunch, I can't imagine the delays in deciding guilt and innocence
Then you would have the problem of senior-junior relationships. Sometimes being on a jury means taking a strong stand in opposition to others - like when everyone thinks the defendant is guilty/innocent - and then you have to convice others you are right or have others pursuade you to change your mind.
None of these are traits (debate being foremost on the list) I have seen Japanese people display in abundance. I'm not saying that they couldn't do a good job on a jury, or couldn't be trusted to act in a fair and just way, but rather that the jury system does not lend itself well to Japanese dynamics as I have experienced them.