Transparency in Parliamentary Voting

We exploit a recent change in voting procedures in one of the two chambers of the Swiss parliament to explore how transparency affects the votes of Members of Parliament (MPs). Until 2013, the Council of States (St nderat) decided by hand rising. While publicly observable at the time of the vote, MPs decisions could only be verified through time-consuming screening of online videos ex post. In 2014 - in the middle of the legislation period, the chamber switched to electronic voting. As MPs decisions are available online, transparency and observability of MP voting increased. Our analysis is based on individual voting behavior from all final passage votes in the 2011-2015 legislation period. In a difference-in-difference framework, the larger chamber, the National Council (Nationalrat), serves as control group. Voting procedures in the latter have not changed since 2007, the legislative text is identical in both chambers. After the reform, members of the Council of States are significantly less likely to deviate from their party line. We also observe a higher probability to abstain even though a strong party line exists. Our results are in line with increased observability of MP votes and higher conformity pressure from parties and party groups.