“D-Day is going to happen in May 2009, and I think people are seriously going to start panicking next year, as citizens actually face the very real possibility of being summoned, and then have to go into this very strange environment, speak in front of authority figures and actually be questioned about their own opinions,” Mr. Precht said. “And I’m concerned that’s going to freak people out.”

With those concerns in mind, some Japanese are trying to teach their compatriots how to argue.

In Hitachiota, a town that is a two-hour ride from Tokyo and is surrounded by rice paddies, a local theater group decided to put on a play that would dramatize the jury experience. Finding nothing in Japanese, the group’s leader, Fusako Kimura, 73, chose “12 Angry Men.”

Ms. Kimura strongly supports the new system. “But, really, I wondered, can Japanese really express what they believe in,” she said. “Can they really express their opinions?”

“To this day, we value harmony,” she said, and, referring to a haiku by Basho, Japan’s greatest poet, she added, “In Japan, to not speak is considered a virtue.”

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.

Judge Tomonao Onizawa, who is the councilor general at the Supreme Court and is participating in a national education campaign, said the new system was in keeping with wider changes to deregulate industries and unleash creativity in Japan.

“Indeed, instead of simply submitting to authority, it’s important for each individual’s abilities to shine, and release this creative energy,” Judge Onizawa said. “In short, to think for oneself and build a reinvigorated Japan.”