A change of the electoral system for the House of Councilors, Japan’s second chamber (or upper house), is under consideration. The proposal has been advanced by the current president of the chamber, Takeo Nishioka.
The current system is a mixed-member majoritarian (MMM, or “parallel”) system, in which the nominal tier is mostly FPTP, but some districts are multi-seat, where SNTV is used. This tier currently elects 73 seats in any given triennial election, and 146 in total, given staggered 6-year terms. Another 48 at any election (thus 96 altogether) are elected in a single national district, using open-list PR.
The proposal would switch to open-list PR entirely, in nine regional districts–implying an average magnitude of 13.4 (121 seats per election in 9 districts). Apparently the national tier would be abolished, along with the nominal tier. No changes would be made to the staggered terms, as that would require a constitutional amendment.
The linked story makes one error, however. It says, “The current system allots seats to candidates according to a list fixed by their party prior to the election.” That implies closed, rather than the (fully) open lists that are used now. I am told by Japanese-literate contacts that the original version of the story did not have that error; so it must be a translators’ error.
The House of Councilors has been quite a laboratory of electoral systems over time. The nominal tier has been consistently FPTP or SNTV (depending on the district), but the national tier used closed lists from 1981 until 2001, when the current open-list system was adopted. Prior to 1981, the national tier was one large SNTV district.
The current nominal tier is quite severely malapportioned, a factor that triggered a Tokyo High Court ruling against the system recently. The impact of the malapportionment is clear from a glance at the 2010 election results. The DPJ and allies actually slightly outperformed the LDP and its allies in votes cast in the nominal tier, yet the LDP(+) won 42 seats to only 28 for the DPJ(+). Some of this may be due to coordination issues in the SNTV districts–discussed here with respect to the 2007 election–but most of it surely is the malapportionment. Of course, a regionalized PR system does not necessarily guarantee a lack of malapportionment, which would depend on how boundaries and magnitudes of districts determined.
Thanks to Kuniaki Nemoto, on his Facebook page, for the tip.