三輪 洋文

Japan is an intriguing case in the literature of judicial independence because of the Liberal Democratic Party's (LDP) long-lasting one-party dominance in government—which, in theory, leads to low independence. Although scholars have found plentiful anecdotal observations implying the LDP's judicial control, quantitative evidence remains scarce. Focusing on the Supreme Court as the first step, this study provides a new dataset on justices' ideal points through an extensive compilation of justices' voting data and application of the dynamic item response theory model. I validate the estimates' interpretability as ideological positions. The results present several novel findings: justices with a career-judge background are relatively conservative; the Chief Justice tends to be particularly conservative; the conservative camp has tended to hold on to a court majority since the 1960s; and the government's partisanship, to some degree, influences appointed justices' positions. These results reinforce scholars' views that Japan's court leans conservatively and aligns with the LDP, with implications for judicial independence in Japan.

In bicameral legislatures, gender representation varies significantly between chambers. Historically, Japan's upper house has maintained a proportion of women twice that of the lower house. However, electoral systems alone cannot fully explain this disparity. We argue that seemingly gender‐neutral legislative institutions influence both voting behavior and candidates' willingness to run, contributing to significant disparities in gender representation in bicameral legislatures. To test this argument, we conduct two survey experiments exploring the underlying mechanisms from the perspectives of voters and candidates. Our findings suggest that informing voters about the upper house's subordinate role increases support for female candidates in upper house elections. Furthermore, women display a greater willingness to pursue office when assured of job security in the upper house, while men exhibit less interest when made aware of its limited authority to appoint the prime minister. This study enhances our current understanding of the effects of asymmetrical institutions between chambers from a gender perspective.

This study examines the effect of perceived military threat on Japanese people’s opinion about Japan’s accession to the Treaty on the Prohibition of Nuclear Weapons. While nuclear aversion has been historically strong and deep-rooted in Japan, we expected that people would hesitate to support the treaty when reminded of the deteriorating security environment, considering recent experimental evidence suggesting that nuclear aversion is conditional and tends to fluctuate often and that Japanese citizens tend to be apathetic towards international laws. Moreover, we examine the possibility that pressure from foreign countries and international organizations reinforces people’s support for the treaty. Our survey experiment reveals that Japanese people are less likely to support Japan’s accedence to the treaty when they are primed with security threats, although the difference is small, and that this negative effect is limited to centrist and conservative citizens. However, we find no evidence that international pressure has the power to promote people’s support for the treaty.

Recent studies in democratic countries suggest that voters generally prefer candidates with specific personal attributes, such as being female and young. However, some of these patterns cannot necessarily be explained by voters’ expectations of candidates’ competence. Building on a growing body of literature that addresses populist attitudes as an important factor influencing voters’ political preferences, this study hypothesizes that candidates’ personal attributes shape voters’ perceptions of their populist attitudes and that such perceptions mediate the relationship between personal attributes and voter preferences. A conjoint experiment conducted in Japan showed that several personal attributes substantially influenced candidates’ perceived anti-elitism and people-centrism. An additional experiment to disentangle causal mechanisms suggested that, albeit inconclusive, young candidates were more likely to be preferred because of voters’ expectations of their populist tendencies. Methodologically, this study illustrates advancements in the conjoint experiment design to elucidate causal mechanisms, with a careful discussion of necessary assumptions.

The incumbent-led subversion of democracy represents the most prevalent form of democratic backsliding in recent decades. A central puzzle in this mode of backsliding is why these incumbents enjoy popular support despite their actions against democracy. We address this puzzle using the case of Philippine President Rodrigo Duterte. Although some Philippine analysts have speculated that his popularity was inflated due to social desirability bias (SDB) among survey respondents, there has been limited empirical examination. Our pre-registered list experiment surveys conducted in February/March 2021 detected SBD-induced overreporting at about 39 percentage points in face-to-face surveys and 28 percentage points in online surveys. We also found that the poor Mindanaoans, and those who believed their neighbors supported Duterte, were more likely to respond according to SDB. These possibly counter-intuitive results should be interpreted with caution because the survey was conducted during the height of the COVID-19 lockdown, and the findings cannot necessarily be extrapolated to the other period of his presidency. Nevertheless, this study suggests that preference falsification could be an alternative explanation for the puzzle of popular incumbents in democratic backsliding.