This study examined the relationship between the amount of legal knowledge, knowl-edge of the lay judge system, cognitive factors (i.e., perceived risk to one's life, perceivedcost to act as a saiban-in "lay judge," perceived benefit to act as a saiban-in), emotions (anxiety, stress, and anticipated regret), and behaviors (i.e., intentions and requests to act as a saiban-in) in the lay judge system. First, we surveyed a sample of 307 citizensin 2007 and 700 citizens in 2012, and compared the decision-making processes in thesetwo years using structural equation modeling. The results indicated that the effect ofperceived benefit to act as a saiban-in on intentions was weaker in 2012 than 2007.In contrast, the effect of perceived cost was stronger in 2012 than in 2007. This may explain why the intention to act as a saiban-in was low in 2012, despite the greater knowledge of saiban-in processes in 2012 than in 2007. Second, the groups in 2012 were (1) males with a decision-making style defined by low responsibility scores, (2) maleswith high responsibility scores, (3) females with low scores, and (4) females with highscores. We examined the decision-making processes among the groups. F