From the Japanese conviction rate, we can conclude that the trials are meaningless. This is, I think, rather different from other civil law countries. But what this means is that the accuracy of the system is in the hands of the police and prosecutor, not the judge. Juries are obviously very different from judges, but police are not so obviously different (they are both professionals employed by the state).

So one should ask if the overall effect is different from other civil law countries and whether this is due to formal differences or informal ones. My impression is that the overall effect is a much higher closure rate, but I haven't seen numbers.