Comparative Jury Decision Rules

The New York Times ran a front page story today analyzing Japan's preparation for the introduction of its new jury system.  The story is interesting, if only because it helps us understand that jury systems need tobe designed with some sensitivity to cultural values that will be shape, in some measure, how well the system functions. 

The decision rule that Japan will employ is interesting in its own right.  It looks nothing like ours -- both because unanimity is not required and because judges and jurors deliberate together:

In the new system, judges and jurors, with one vote each, will decide cases by a simple majority. Jurors can ask questions in the courtroom, and through their numbers can effectively overrule the judges. Even though all three judges may rule that a defendant is guilty in a case, a not-guilty ruling by at least five of the jurors will prevail. The only exception involves a guilty ruling: even if all six jurors vote guilty, the ruling will not stand unless at least one of the three judges shares that verdict.

Obviously, there are many debates about the right decision rule and whether jurors should be able to deliberate away from judges.  But this summer I finally completed my comparative study of world jury systems in the large democracies.  What I learned is that unanimity is extremely anomolous (existing only in the US, Canada, and few jurisdictions in Australia).  Also notable is that the more newly designed systems that are entering the world stage – in Spain, Russia, Japan, and South Korea – do not use unanimity as their preferred decision rule.  Finally, the world's democratic jury systems are essentially even-divided among "pure" juries, where jurors deliberate by themselves -- and "mixed" juries, where jurors deliberate with judges.

I'll post the study to SSRN soon; it collects for the first time in English a comprehensive analysis of the jury system choices in the large democracies.  If you just need a fix of great stuff on decision rules, check out Adrian Vermeule's blog post at the Oxford University Press website here; Adrian's blogging about his newest book Mechanisms of Democracy: Institutional Design Writ Small, a book that looks extremely interesting.  I'll let you know more about it as soon as I get a chance to read it.