Study on mock jurors' understanding of Proof beyond a reasonable doubt standard

The ‘Civil Participation in the Criminal Trial Act’ (the Act) passed the National Assembly of Korea on April 30, 2007, and it has come to effect on Jan. 1, 2008. The Act enabled lay persons to take part in decisions in serious criminal trials. The jury trial is a new system in Korean history. In this sense the introduction of the jury system is regarded as a significant change of the judiciary system. Even though the new Korean jury system does not take the conventional form of the English or American jury-a kind of hybrid system of the German mixed judge tribunal and the American jury. The jury deliberates without judges at the first stage. So jury instructions are important and crucial to ensure the fair and correct verdicts and sentences. This research involves 334 college students, and 519 adults, and three versions of instructions on the proof standard of beyond a reasonable doubt are employed. The results show that mock jurors understand the standards slightly differently by versions. We can conclude that sophisticated and empirically tested jury instructions are needed to enhance jury understanding of the standard of proof beyond a reasonable doubt as well as other criminal principles.