Traders may be able to call upon guidelines from the Supreme Court to be excused from the new lay judge system, on grounds that they are critical to the functioning of financial markets.
The system that went into effect Thursday pairs citizen jurors, or lay judges, with professional judges to decide criminal cases. The nation's highest court handed guidelines to district courts on who may be excused from duty in jury trials, enabled by 2004 legislation for implementation this year.
Among situations a trader may request exemption for include when special quotations must be fixed after a significant rise in trading volume, or on days when monetary policy and market-moving statistics are released, the guidelines say.
The Supreme Court said that important trading opportunities could be missed if skilled workers are absent for jury duty.
"If a person's skill is so essential that no one can substitute, the exemption would be justified," said Toshikuni Murai, criminal law professor at the law school of Ryukoku University in Kyoto.
The court listed what it considered valid reasons for jury exclusion of people in 187 work categories.
"To serve our clients, we must stay in the office when events occur that could shake stock markets," said Sadao Hada, a manager overseeing equities trading at SMBC Friend Securities Co. in Tokyo. "We would like to be exempt from jury duty on these occasions."