Over the last two decades, jury systems have been introduced in Spain, Japan, Korea, and, on a provisional basis, in Taiwan. Why might states with criminal trials that have been dominated by professional judges allow greater public input into their criminal proceedings? There also exist important differences in the jury systems in the three countries; for instance, while defendants in Japan cannot opt out of a jury trial if they are accused of a certain class of cases, defendants in South Korea may choose whether or not to be tried by a jury. What factors account for the differences in the configuration of new jury institutions across different countries? The present study conducts detailed process-tracing from Spain, Japan, South Korea, and Taiwan to argue that partisan dynamics, especially the relative influence of left-libertarian parties, crucially shaped both the timing and the configuration of jury systems in the four countries.
