The Supreme Court has upheld two separate rulings that overturned death sentences handed down in lay judge trials to two men facing robbery-murder charges.

It is the first time a death penalty issued by a panel involving citizen judges has been nullified by the Supreme Court since the lay judge system was introduced in Japan in May 2009 to reflect "common sense" in criminal trials, which have often been criticized for being difficult to comprehend and out of touch with popular sentiment.

On the decision reached Tuesday, the top court said a death sentence is "an ultimate punishment that takes the defendant's life" and judges "need to carefully consider it and show concrete evidence" that the punishment cannot be helped.